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At 750°C and a pressure of 1 kbar, an experiment was carried out simulating the contact-reaction interaction of calcite and a highly evolved fluorine-containing granite melt. The water content in the system did not exceed 10% of the dry charge mass. The possibility of interaction between magmatic melt and calcite is shown. The experimental products contain a zoned column composed of liquid phases and crystalline minerals. In the apocarbonate part, the newly formed phases are cuspidine, quartz, wollastonite, grossular, and a non-crystalline carbonate–fluoride phase LCF. The mineral assemblages in the zones of the apocarbonate part of the column vary depending on the ratio of CO2 and HF activities. In the silicate part, aluminosilicate glass, alkali feldspar, and plagioclase of variable composition were found. Silicon and fluorine are intensively transferred from the silicate to carbonate part, and a small amount of calcium is transferred in the opposite direction. [ABSTRACT FROM AUTHOR]

The thermal conductivity of natural monoliths of calcite, dolomite marble, and limestone from various deposits was measured using the absolute stationary method of longitudinal heat flow in the temperature range of 50–300 K and the dynamic method in the range of 323–573 K. A majority of calcite marbles were inferior in thermal conductivity to dolomite marbles. At room temperature, the thermal conductivity coefficients of all studied samples were lower k = 5 W/(m K). The obtained data were compared with the literature data. The diversity of experimental data from different authors on the thermal conductivity of carbonates is associated with qualitative differences in the samples studied

Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam), synthesized from O-methyl-N-(pyridin-2-ylmethyl)oxamate, was spectroscopically and structurally characterized and assayed as a novel precursor for the protection and consolidation of carbonate stone substrates. An in-depth characterization of treated and untreated biomicritic limestone and white Carrara marble samples was carried out by means of SEM microscopy, X-ray powder diffraction, helium pycnometry, determination of water transport properties, and pull-off tests. The improved solubility (1.00 M, 16.5% w/w) of the title compound with respect to ammonium oxalate (0.4 M, 5% w/w) results in the formation of a thicker protective coating of calcium oxalate (CaOx) dihydrate (weddellite) on marble and biomicrite samples after the treatment with 5% and 12% w/w water solutions, producing a reduction in the stone porosity and increased cohesion. Theoretical calculations were carried out at the DFT level to investigate both the electronic structure of the N-(pyridin-2-ylmethyl)oxamate anion and the hydrolysis reaction leading from AmPicOxam to CaOx. [ABSTRACT FROM AUTHOR]

Various marbles from historic quarries of the Czech Republic were examined by means of cathodoluminescence (CL) spectroscopy (quantitative data) to determine the possible inclusion of the method in marble provenance studies. The methodology used was based on a combination of electron microprobe analysis (Ca, Mg, Fe and Mn composition) and CL spectroscopy (intensity) of calcite and dolomite grains of the marbles studied. Several statistical techniques were applied to the CL-spectra to find the most effective way of characterization of the CL-spectra for provenance discrimination. The combination of Mg-admixture of calcite and position of the maximum (i.e., centre) of a single Gaussian curve was revealed to be the most discriminative dependence of the marbles studied. [ABSTRACT FROM AUTHOR]

Almost all igneous rocks are composed of silicate minerals; carbonatites are the main exception to this rule. They form only a minor proportion of the continental crust but are of fundamental scientific and economic importance. These rocks, originally described as a limestone (Kaiserstuhl, Germany) or magmatic limestone (Alnö, Sweden), were recognized in 1921 by W. C. Brøgger as a distinct magmatic rock type under the name "Karbonatite" in the Fen complex (Norway). Extensive field mapping in Africa, and particularly studies within the Chilwa Alkaline Province (Malawi), have led to the discovery of diverse intrusive and extrusive carbonatites. The latter, including the Fort Portal volcanic field in Uganda, Rufunsa Province in Zambia, and Oldoinyo Lengai volcano in Tanzania (the only volcano ever to have been seen to erupt carbonatites), have been exceptionally important in the recognition of carbonatites as truly magmatic rocks. The possibility of the existence of carbonate melts has been confirmed and shown by experimental studies of diverse carbonate systems with added volatile components (H 2 O, F) and alkali elements (Na, K). The study of the Oldoinyo Lengai gregoryite-nyerereite carbonatites, which are mineralogically and compositionally different from all known carbonatites worldwide, has led to long-lasting discussions about the origin of carbonatites. This includes composition of primary/parental carbonate melt, derivation of carbonatites by either liquid immiscibility or fractional crystallization, carbonatite evolution, and especially, the possible genetic relationships between alkali-rich and alkali-poor carbonatites. The rapid alteration of Oldoinyo Lengai carbonatites and their transformation to calcite carbonatite-like rocks has been proposed as the explanation for the absence of alkali-rich carbonatites in the geological past. Detailed mineralogical studies have shown that the occurrence of nyerereite is not restricted to Oldoinyo Lengai and that this mineral is now known to occur in other carbonatites (e.g., Guly, Kovdor, Oka, Kerimasi), alkaline rocks, and kimberlites (and even in diamond). This would suggest compositionally different mantle-derived melts enriched in alkali elements. In addition, carbonatite tephra has an important role in the preservation of some key paleontologic and anthropologic localities in East Africa. Despite these important discoveries, several problems related to carbonatite petrogenesis are not yet resolved. Future work is required, and carbonatites within Africa, with its key localities, may help to solve these problems. • The Kaiserstuhl volcano is the first locality where carbonatites were described in 1783. • Field observations are the key evidences for recognition of carbonatites as magmatic rocks. • Oldoinyo Lengai is the only active volcano that erupts gregoryite-nyerereite carbonatite. • Alkali-rich carbonatites are important for the understanding of carbonatite genesis and evolution. • Existence of compositionally different carbonatite melts is confirmed by experimental studies. [ABSTRACT FROM AUTHOR]

Related to the letters of an alphabet, entropy means the average number of binary digits required for the transmission of one character. Checking tables of statistical data, one finds that, in the first position of the numbers, the digits 1 to 9 occur with different frequencies. Correspondingly, from these probabilities, a value for the Shannon entropy H can be determined as well. Although in many cases, the Newcomb–Benford Law applies, distributions have been found where the 1 in the first position occurs up to more than 40 times as frequently as the 9. In this case, the probability of the occurrence of a particular first digit can be derived from a power function with a negative exponent p > 1. While the entropy of the first digits following an NB distribution amounts to H = 2.88, for other data distributions (diameters of craters on Venus or the weight of fragments of crushed minerals), entropy values of 2.76 and 2.04 bits per digit have been found. [ABSTRACT FROM AUTHOR]

Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam), synthesized from O-methyl-N-(pyridin-2-ylmethyl)oxamate, was spectroscopically and structurally characterized and assayed as a novel precursor for the protection and consolidation of carbonate stone substrates. An in-depth characterization of treated and untreated biomicritic limestone and white Carrara marble samples was carried out by means of SEM microscopy, X-ray powder diffraction, helium pycnometry, determination of water transport properties, and pull-off tests. The improved solubility (1.00 M, 16.5% w/w) of the title compound with respect to ammonium oxalate (0.4 M, 5% w/w) results in the formation of a thicker protective coating of calcium oxalate (CaOx) dihydrate (weddellite) on marble and biomicrite samples after the treatment with 5% and 12% w/w water solutions, producing a reduction in the stone porosity and increased cohesion. Theoretical calculations were carried out at the DFT level to investigate both the electronic structure of the N-(pyridin-2-ylmethyl)oxamate anion and the hydrolysis reaction leading from AmPicOxam to CaOx.

The Lenadora quarry, located 25 km north of Matale, in central Sri Lanka, exploits dolomitic marble on an artisanal scale. It is located in the Highland Complex but very close to its thrust contact with the Wanni Complex. The rocks have undergone metamorphism to the granulite facies; by analogy with metasedimentary rocks in a similar position south of Kandy, conditions of metamorphism may even have surpassed 900°C and 0.9 GPa. How did dolomitic marble fare in such an ultrahigh-temperature environment? High-resolution large-area image mosaics of imaged polished thin sections were acquired by using both light microscopy and scanning electron microscopy. We focus on fifty areas of interest. As expected, diopside and forsterite porphyroblasts appeared during prograde metamorphism. However, we did not anticipate to see subhedral porphyroblasts of forsterite mimetically replaced by diopside + dolomite. The conversion could have involved a fluid phase or a carbonate melt that had become locally enriched in silica. The presence of a melt accounts for composite calcite + dolomite globules trapped in forsterite. There is no evidence of breakdown products of dolomite, like periclase or brucite. The evidence that a carbonate melt was present is circumstantial; carbonate systems are notorious for erasing telltale evidence of melting. Other minerals encountered in the dolomitic matrix are phlogopite, pargasite, rutile, hydroxylapatite, zirconolite, lakargiite, a magnesiobeltrandoite-like phase, pyrrhotite, and calcite as a minor phase, some of which is of a second generation. Unreplaced relics of forsterite were partially serpentinized at a retrograde stage. [ABSTRACT FROM AUTHOR]

Impure dolomitic marble from the Great Himalayan Sequences (GHS) in Thongmön area, central Himalaya, is first systematically reported here concerning its petrographic features, textural relations, and fluid evolution. The Thongmön impure marble is characterized by the assemblage of calcite + dolomite + forsterite + spinel + phlogopite + clinohumite ± diopside ± retrograde serpentine. Three groups of calcite and dolomite occurring both as inclusions and in the matrix were identified: group I is represented by relatively magnesium-rich calcite (Cal) (CalI:XMg = 0.10–0.15) and almost pure dolomite (Dol) (DolI:XMg = 0.47–0.48), corresponding to the Cal-Dol solvus temperatures of 707–781 °C; group II is characterized by vermicular dolomite exsolutions (DolII:XMg = 0.45–0.46) in Mg-rich calcite and Mg-poor calcite (CalII:XMg = 0.05–0.08) adjacent to DolII, and the recorded solvus temperatures are 548–625 °C; group III is represented by nearly pure calcite (CalIII:XMg = 0.003–0.02) and Ca-rich dolomite in the matrix (DolIII:XMg = 0.33–0.44). Isobaric T-X(CO2) pseudosection at a peak pressure of 15 kbar in the system K2O-CaO-MgO-Al2O3-FeO-SiO2-H2O-CO2 suggests that the peak fluid composition of the Thongmön forsterite marble is restricted to X(CO2) < 0.04 at T > 780 °C due to a potential infiltration event of H2O-rich fluid. Alternatively, the forsterite marble is a retrograde product subordinated to the GHS exhumation process, and its fluid composition is relatively CO2-rich (0.6 < X(CO2) < 0.8 at 5 kbar, 750 °C) at a nearly isothermal decompression stage. In either case, we suggest that the carbon flux contributed by metacarbonate rocks in an orogen setting to the global carbon cycling must be considered. [ABSTRACT FROM AUTHOR]

Calcite twinning is a dominant deformation mechanism at low temperatures. It is often used to reconstruct paleostresses: orientations of the principal stress axes, stress ratios and differential stress. Despite numerous studies, on single crystals and aggregates, questions remain about the initiation and evolution of the twinning. In particular, the existence of a critical value for the activation of twin planes is debated. In this study, Carrara marble samples were uniaxially deformed at low temperature. The experiments were monitored in situ in an SEM (Scanning Electron Microscope) and a deformation analysis was performed at regular intervals using image correlation. Image correlation analysis shows the link between the overconcentration of strains and the appearance of the first twinned planes. This is followed by a densification and a gradual thickening of the twin lamellae. Fracturing only appears in a third stage as a precursor to the collapse of the sample. The inversion, using the CSIT-2 technique, showed that the twinned planes are globally related to the applied macroscopic stress. The inversion allows one to retrieve the macroscopic stress tensor. Schmid factors were extracted from this analysis and correlated to the loading curves. For crystals of about 200 µm diameter, the threshold value is in between 6.75 and 8.25 MPa. [ABSTRACT FROM AUTHOR]

• Calcite bodies (CBs) consistently appear within a marble band of the UHT granulite facies metamorphic terrain of the Highland Complex (HC) in Sri Lanka. • The trace element and isotopic compositions of the CBs show distinctions from typical mantle-derived carbonitites, but indicating crustal sources. • These findings suggest that the CBs should be derived from the crustal anatexis of marble. • The UHT metamorphism, along with the presence of CO 2 -rich fluids, likely facilitated the crustal anatexis of marble. The special calcite bodies (CBs) exposed within the ultrahigh temperature (UHT) granulite facies terrain in the Balangoda area of Sri Lanka preserve shreds of evidence for the generation of crust-derived carbonatite in the crust. The CBs are exclusively made up of massive calcites and appear as concordant bands extending tens of meters or as meso -scale isolated pockets hosting the massive dolomitic marble band. Various sizes of mafic and calc-silicate enclaves occur as rotated or tilted structures within the CBs. The contact between the CBs and the host marble is texturally and mineralogically gradational, while the contact between the enclaves and the CBs is sharp. The large-ion lithophile elements and rare earth element contents of the CBs show enrichment compared to the host marble, while depletion compared to typical carbonatites. Furthermore, the Sr content and C-O isotope values in CBs differ from those found in known carbonatites, hydrothermal carbonates, or metasomatic carbonates. We suggested that the crustal anatexis of marble should be hypothesized as the possible mechanism for the origin of the CBs. Microtexural evidence of the calcite grains shows indications of the melting of the host marble. The release of CO 2 -rich fluids from the collision and thrusting of HC over VC, or related metamorphic events, likely lowered the solidus of carbonates, triggering crustal anatexis of marble during UHT granulite facies metamorphism. The generated low viscous carbonate melt may have moved rapidly, resulting in a low degree of mixing of silicates and fragmentation and dislocation of enclaves. The results of the present study reflect the existence of anatexis of carbonates under extreme crustal conditions and provide a better understanding of the sources, migration paths and reservoirs of the carbon recycling processes. [ABSTRACT FROM AUTHOR]

Various marbles from historic quarries of the Czech Republic were examined by means of cathodoluminescence (CL) spectroscopy (quantitative data) to determine the possible inclusion of the method in marble provenance studies. The methodology used was based on a combination of electron microprobe analysis (Ca, Mg, Fe and Mn composition) and CL spectroscopy (intensity) of calcite and dolomite grains of the marbles studied. Several statistical techniques were applied to the CL-spectra to find the most effective way of characterization of the CL-spectra for provenance discrimination. The combination of Mg-admixture of calcite and position of the maximum (i.e., centre) of a single Gaussian curve was revealed to be the most discriminative dependence of the marbles studied.

Proterozoic high‐grade marbles cover a significant portion of the Highland Complex (HC) of Sri Lanka. Although many studies on metamorphic silicate rocks of the country have been carried out, marbles, which can be used as a tool to interpret the evolution history of the crust, has been paid little attention. The present study aims to understand the genesis and characteristics of protolith of these marbles by investigating their mineralogy and geochemistry. The studied marbles occur as bands intercalated with pelitic gneisses and quartzites of the HC, indicating the pre‐existing sandstone‐shale‐carbonate sedimentary sequence. Except along the lithological contacts, the studied marbles contain low amounts of silicate minerals (<5%) and are dominated by dolomites (>90%) with minor calcites. Calcites occur as inclusions within dolomites or as fine grains along the grain boundaries of dolomites. Silicate minerals always occur as lensoid or layered aggregations. Dolomites are related to the protolith composition, while most of the calcites are metamorphic products formed due to the reaction of silicate minerals with dolomite. Silicate mineralogical zones suggest the inherited compositional variations of the protolith. Although the marbles have undergone granulite‐grade metamorphism, their trace elemental contents have been well preserved. Concentrations of Fe, Mn, Sr, Na, and K as well as rare earth element (REE) contents of the marbles are comparable to those of marine origin carbonates. Hence, marine dolostone can be proposed as the protolith for Sri Lankan marbles. The distinct mineralogy as well as elevated trace element and REE concentrations of marble in the lithological contact zones are evidenced for prevailed syn‐ to post‐metamorphic fluid activities in the HC. Mineralogical and trace elemental composition of Sri Lankan marbles are correlated well with the marbles from other East‐Gondwanaland crustal units. [ABSTRACT FROM AUTHOR]

Comprehensive petrological and isotope-geochemical study of marble was carried out in the upper part of the Sortavala Group of the northeastern lense at the Ruskeala deposit in the Northern Ladoga area. The petrological study showed that the carbonate rocks of the Sortavala Group underwent medium-temperature low-pressure amphibolite-facies metamorphism. The mineral assemblages of Ruskeala marbles were formed at temperature of 550–600°C and pressure of ~3–5 kbar in equilibrium with a mixed water-carbon dioxide fluid with ~ 0.5–0.8. Dolomite marbles contain admixture (up to 2%) of finely disseminated carbonaceous matter and about 8–15% of calcite. Dolomites contain small amounts of Mn (70–110 ppm) and Fe (1600–3600 ppm) and high content of Sr (122–256 ppm). The initial 87Sr/86Sr ratio in the dolomites is within 0.70465–0.70522, δ13C values vary between +0.6...+1.9 ‰, and δ18О within –13.2 ... –10.2‰ (V-PDB). Calcite marbles are free of carbonaceous matter, have very low contents of Mg (0.2–0.8%), Mn (10–90 ppm) and Fe (160–640 ppm) and very high Sr concentration (850–2750 ppm). The initial 87Sr/86Sr ratios in the calcite marbles range from 0.70482 to 0.70489, δ13С from 1.5 to 2.1‰, and δ18О from –10.9 to ‒8.1 ‰ (V-PDB). Tremolite-bearing marbles have higher 87Sr/86Sr ratio (up to 0.70522), while their δ13С and δ18О values decrease to 0.1‰ and –12.2‰, respectively. The metamorphism of Ruskeala carbonate even under medium-temperature amphibolite-facies conditions was essentially isochemical process, which retained the unique Sr and C chemostratigraphic potential of calcite and dolomite marbles for the reconstruction of 87Sr/86Sr and δ13C in the Paleoproterozoic seawater. The 87Sr/86Sr ratio in the 1.9–2.0 Ga Svecofennian ocean was 0.70463–0.70492, and δ13С value +1.5 ± 1‰. New Sr-isotope data record an increase in radiogenic Sr input in the ocean about 2 billion years ago, which was probably related to the growth of continental crust and more intense weathering. The δ13С in Ludicovian carbonates mark the beginning of C-isotope stasis in ocean after the Lomagundi-Jatulian anomaly of 13Ccarb. [ABSTRACT FROM AUTHOR]

In order to correct aggressive water destined for consumption by remineralization, the kinetics of dissolution of marble, an available material primarily made of calcite, were determined. Two types of marble were characterized by FTIR and X-ray spectroscopy and by chemical analysis, and then employed for the kinetics studies at room temperature and pH 1, 3 and 5, in synthetic solutions of hydrochloric acid diluted with distilled water. Dissolution was carried out in agitated reactor at 105 rpm; in which were plunged electrodes for pH and conductivity measurements. Six different particle sizes were dissolved for each type of marble (from 0.1 up to 3.15 mm). The results obtained indicated that dissolution rate increased with an increase in pH and a decrease in particle size. The kinetics of calcium in river and distilled water permitted to discover that the dissolution of calcium followed the second rate reaction model 1/ ([Ca]t - [Ca]s) = k2t + 1/[Ca]t + [Ca]O. The principal criteria for the choice of the best marble were the mineralogical and chemical composition of the material.

Marbles in Pohorje occur in lenses and smaller bodies in the southern and southeastern part of the massif. Marbles are very pure, predominantly calcitic and rarely calcitic-dolomitic, containing a maximum of 5 % of non-carbonate mineral phases. The latter comprise pyroxenes (diopside), amphiboles (tremolite), olivines (forsterite) in places replaced by serpentine, quartz, feldspars (potassium feldspars and plagioclases), epidote, zoisite, vesuvianite, scapolite, muscovite, biotite partly replaced by chlorite, phlogopite, rare grains of titanite, rutile, zircone, apatite, and small grains of ferric oxides and sulfies. Calcite exhibits intensive deformational e-twinning whereas dolomite is undeformed and untwined. All four known types of mechanical twins in calcite were recognized: thin Type I twins, straight thick Type II twins, curved, lensoid and tapered thick Type III twins, and thick patchy Type IV twins. Type III twins are the dominant mechanical twins in the Pohorje marbles indicating the temperature of deformation somewhat above 200 °C. Since they lack signs of grain boundary recrystallization, we assume that the twinning was followed by a decrease temperature during exhumation. With increasing temperature the process of recrystallization along calcite grain becomes pronounced. Small individual untwined calcite crystals are progressively replacing bigger calcite grains. In few examples second generation of Type I deformational twins develop in recrystallized calcite grains, which also implies lowering of temperature due to exhumation.

Calcite powders were prepared from black marble waste by milling and alkaline hydrothermal processes. Crystal modifiers including two sulfates and an organophosphate chelator were used to study their effects on the crystallinity and particle morphology of calcite powders. Compared with control experiments without crystal modifiers, the Na 2 SO 4 modifier drastically decreased the crystallinity of calcite powder, while the organophosphate modifier distinctly decreased the brightness and crystallite size of the calcite powder. Besides the rhombohedral crystallites, the calcite powders with sulfate modifiers contained a few flocculent agglomerates and nanosheets, which were assigned to amorphous/vaterite phases and portlandite phase, respectively. The organophosphate modifier induced spherical nanocrystals instead of the rhombohedral crystallites. With hydrothermal treatment performed for 4 h at 240 °C, nanosized calcite powder (88.3 nm) with a powder brightness of 94.3% was achieved at 1% organophosphate modifier. The eco-friendly technique enables the scalable recycling of marble wastes into nanosized calcite powders. Unlabelled Image • Black marble waste was used as the starting material of calcite powders. • The addition of Na 2 SO 4 modifier reduced the crystallinity of calcite powders. • The crystal modifiers significantly affected the particle morphology. • The chelator modifier produced nanosized calcite powders with high brightness. • The dissolution-recrystallization process occurred at 200 °C. [ABSTRACT FROM AUTHOR]

Natural calcium carbonates have a great importance in the world's economy due to their numerous applications areas such as calcium carbonate in the paper and paint industries. The final calcite products have rigorous quality specifications which are currently difficult to meet for local producers in Turkey. Therefore, large quantities of high white marble wastes have been transported long distances inside the country to supply the different industrial plants for using calcite. Marble wastes, located in Afyon and Kutahya regions, Turkey's mid-west, are used generally for concrete and highway purposes. Evaluations of marble wastes are very important for the economic development of any country or region. This study aims at developing new perspective for evaluation of marble wastes as domestic calcite resources and serves as a guide for investment and decision making for the Turkey calcite industry. This paper presents applied research work to determining the product quality for evaluation as micronized calcite of marble wastes and gives an overview of the market situation for the regional producers. The aim of the work is to characterize four different marble wastes and to determine the potential for production of the required quality for the Turkey calcite market;- to control the quality of the products by application tests, including the measurement some tests. [ABSTRACT FROM AUTHOR]

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[Display omitted] • Isotope reordering in calcite and dolomite marbles is independent of mineral grain sizes, crystal lattice defects, and subjected active stress. • Calcites and dolomites have blocking temperatures of 211 and 332 °C, respectively. • The inferred cooling rates are 614 and 8.8 × 104 °C/m.y. for calcites and dolomites, respectively. Clumped isotopic compositions (abundance of 13C16O18O in CO 2 , expressed by Δ 47) in massive calcite marble (CM) and dolomite marble (DM) were reported to refine our understanding of greenschist-facies metamorphism during the still on-going arc-continent collision from the northern, central, and southern localities along the northern-central Tailuko belt of the Backbone Range of Taiwan. Black calcite marble (BCM), white calcite marble (WCM), and DM lenses with cataclastic texture were analyzed. We observed that the carbonate clumped isotope reordering is independent of the grain size of minerals and is less likely affected by lattice defects and active stress. The averaged Δ 47 values for CMs and DMs are 0.308 ± 0.004 ‰ (n = 26) and 0.235 ± 0.003 ‰ (n = 13), respectively, giving blocking temperatures of 211 ± 6 °C and 332 ± 8 °C. The blocking temperatures infer mean cooling rates of 614 °C/m.y. and 8.8 × 104 °C/m.y for calcites and dolomites, respectively, estimated based on the available models and clumped reordering mechanisms. We noted that the variations in cooling rates widely differ with different reordering models, especially with different temperature calibrations. Some cooling rate estimates are in agreement with those based on zircon/apatite thermochronological studies. Further refinements on Δ 47 - temperature calibration, reordering mechanism and estimation of thermodynamic constants, in addition to improvement in analytical precision, are needed for practical applications of carbonate clumped thermometry as a tectonic speedometer for metamorphic terranes. [ABSTRACT FROM AUTHOR]

This study investigated the poorly known phenomenon of Centimetric circular areas Uncolonized by Microbial Biofilms (CUMBs) which is frequently observed on natural and heritage stone surfaces displaying widespread lithobiontic colonization. In order to unveil a possible relationship with past lichen colonization, analyses were carried out on the distribution, morphometry, physical and mineralogical properties, and microscopic features of CUMBs on the marble surfaces of a balustrade in the Garden of a Savoy residence in Torino (Italy; UNESCO-WHS 823bis) and in its original quarry site in the W-Alps. Image analyses of CUMBs displayed a distributional and dimensional compatibility with lichen thalli (re-)colonizing surfaces in their vicinity. Invasive analyses on quarry materials displayed similar microscopic modifications in marble layers beneath CUMBs and lichens, associated to a higher stabilization of the calcite {01–12} form, which is favoured by the presence of organic substances. These findings support the hypothesis of a lichen origin for some CUMBs, which may derive from the modification of physical stone properties and/or a long-lasting allelopathic effect affecting surface bioreceptivity. [Display omitted] • CUMBs and lichens compared on natural and heritage marble surfaces. • Distributional and dimensional compatibility of CUMBs and lichens. • Similar micro-features beneath CUMBs and lichens associated to calcite reprecipitation. • Experimental evidences pointing to a lichen origin of (some) CUMBs. • Reduced CUMBs bioreceptivity due to modified physical properties and/or allelopathy. [ABSTRACT FROM AUTHOR]

When marble is cleaned by nanosecond neodymium yttrium–aluminum–garnet lasers (1064 nm), strongly absorbing surface contaminants are removed at fluences substantially below the damage threshold for the much less absorptive marble substrate. Recent studies have shown, however, that unacceptable roughening of the marble surface also may occur at low fluences due to removal of individual grains. In order to elucidate this effect, we have compared the low-fluence response of marbles with two different grain sizes and single-crystal calcite, in the fluence range 0.12–1.25 J cm-2. Damage was greater in fine-grained than coarse-grained marble, and did not occur in the single-crystal calcite at these fluences. The temperature rise following defect-mediated absorption triggers thermal plasma emission and generates shock waves; the concomitant surface damage depends on the size and crystallographic orientation of the crystals. Laser irradiation anneals the defects and increases “crystallite size.” The implications for the laser-assisted cleaning of marble artworks are outlined. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Calcite-graphite carbon isotope thermometry results are presented for 150 new marble samples across the western Central Metasedimentary Belt (CMB) of the Ontario segment of the Grenville Province. The results show a gradual increase in peak metamorphic temperature from under 500 °C in the Tudor Township area in the east to over 700 °C along the western margin of the CMB. Modestly elevated d13C values above 3‰ across all terranes in the study area suggest a common temporal, and perhaps depositional origin, for the ~1.3 Ma limestone protoliths. The preserved thermal gradient is consistent with variations in marble mineralogy and character. Based on published geochronology, we argue that these temperatures correspond to peak metamorphism during the 1090–1020 Ma Ottawan orogeny, with the exception of preserved contact aureoles most notably associated with the Tudor gabbro and the Cheddar granite. The lack of significant thermal discontinuities at terrane boundaries and other shear zones, including the Bancroft shear zone and the CMB boundary zone, indicate that the entire region including the adjacent Central Gneiss Belt remained largely intact during and after the Ottawan peak metamorphic event. Variations in deformation style of pre-existing igneous complexes appear to correspond to the Ottawan thermal conditions, which include crystalline thrust sheets at high temperature, and mildly foliated domes to undeformed plutons at decreasing temperatures. In light of the peak temperatures and smooth thermal gradient we show to be superimposed on the established Grenvillian architecture, much of the western CMB should be considered part of the allochthonous medium pressure belt, and separate from the Ottawan orogenic lid that defines the eastern CMB. [ABSTRACT FROM AUTHOR]

Highlights • Three calcium carbonate sources were employed to study their anticorrosive behavior. • Three techniques were used which are EIS, SEM/EDAX and accelerated lab test. • Their effect on mechanical properties was also studied. • Results showed that egg shell offered the best anticorrosive performance. Abstract Great progress has been devoted recently in corrosion protection of metals via using cheap and efficient protective organic coatings. Calcium carbonate is common filler used in coatings industry due to its distinctive properties and the variation of its sources. The scope of this work is to study the effect of calcium carbonate developed from different sources (e.g. natural calcite, marble and egg shell wastes) on the corrosion protection performance of anticorrosive coatings. The different calcium carbonate sources were characterized using different analytical techniques, such as X-ray diffraction (XRD), X-ray fluorescence, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The three calcium carbonates were then incorporated in solvent-based paint formulations using medium oil-modified soya-bean dehydrated castor oil alkyd resin. The physico-mechanical properties of dry films were tested. Immersion test, electrochemical impedance spectroscopy and SEM/EDAX were used to inspect the corrosion protection performance of coatings containing the three sources of calcium carbonate. The results showed that the corrosion efficiency of egg shell was the best among the three sources due to its unique particle shape structure. [ABSTRACT FROM AUTHOR]

The article offers information on the Pyrites Mica mine on the James Kelly farm near the village of Pyrites in the Town of Canton, Saint Lawrence County, New York. Topics include the phlogopite deposits sit at or near the contact between a marble unit and a pelitic gneiss and close to a leucogranite mass, and mineral found include calcite, clinochlore and dravite.

The onset of frictional failure and potentially seismogenic deformation in carbonate rocks undergoing exhumation within fault zones depends on hardening processes that reduce the efficiency of aseismic dislocation-mediated deformation as temperature decreases. However, few techniques are available for quantitative analysis of dislocation slip system activity and hardening in natural tectonites. Electron backscatter diffraction maps of crystal orientations offer one such approach via determination of Schmid factors, if the palaeostress conditions can be inferred and the critical resolved shear stresses of slip systems are constrained. We analyse calcite marbles deformed in simple shear within the Karakoram Fault Zone, NW India, to quantify changes in slip system activity as the rocks cooled during exhumation. Microstructural evidence demonstrates that between ∼300 °C and 200–250 °C the dominant deformation mechanisms transitioned from dislocation-mediated flow to twinning and frictional failure. However, Schmid factor analysis, considering critical resolved shear stresses for yield of undeformed single crystals, indicates that the fraction of grains with sufficient resolved shear stress for glide apparently increased with decreasing temperature. Misorientation analysis and previous experimental data indicate that strain-dependent work hardening is responsible for this apparent inconsistency and promoted the transition from dislocation-mediated flow to frictional, and potentially seismogenic, deformation. [ABSTRACT FROM AUTHOR]

Marbles in Pohorje occur in lenses and smaller bodies in the southern and southeastern part of the massif. Marbles are very pure, predominantly calcitic and rarely calcitic-dolomitic, containing a maximum of 5 % of non-carbonate mineral phases. The latter comprise pyroxenes (diopside), amphiboles (tremolite), olivines (forsterite) in places replaced by serpentine, quartz, feldspars (potassium feldspars and plagioclases), epidote, zoisite, vesuvianite, scapolite, muscovite, biotite partly replaced by chlorite, phlogopite, rare grains of titanite, rutile, zircone, apatite, and small grains of ferric oxides and sulfides. Calcite exhibits intensive deformational e-twinning whereas dolomite is undeformed and untwined. All four known types of mechanical twins in calcite were recognized: thin Type I twins, straight thick Type II twins, curved, lensoid and tapered thick Type III twins, and thick patchy Type IV twins. Type III twins are the dominant mechanical twins in the Pohorje marbles indicating the temperature of deformation somewhat above 200 °C. Since they lack signs of grain boundary recrystallization, we assume that the twinning was followed by a decrease temperature during exhumation. With increasing temperature the process of recrystallization along calcite grain becomes pronounced. Small individual untwined calcite crystals are progressively replacing bigger calcite grains. In few examples second generation of Type I deformational twins develop in recrystallized calcite grains, which also implies lowering of temperature due to exhumation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption of ethanol, isopropanol and acetone on the calcite surface was modelled. • Alcohols form a hydrophobic layer on calcite, while acetone forms a mixed layer. • Efficacy of solvents for marble protective treatment was experimentally tested. • All solvents favour formation of protective calcium phosphate layer. • The solvent behaviour at surface was proven to have no major effect on treatment. When exposed outdoors, marble artefacts are subject to degradation caused by dissolution in rain. To improve acid-resistance of marble, surface treatments involving the in situ formation of a passivating calcium phosphate (CaP) layer have been developed. Adding alcohol to the treatment improves CaP coverage but the reason is still unclear. Here, we use computational and experimental studies to ascertain whether the interaction of the organic additives with the marble surface plays a role in determining the treatment outcome. Density functional theory calculations are employed to determine the binding energy of additives on the calcite [ 10 1 ¯ 4 ] surface and identify acetone as a promising new additive due to its weak adsorption. Molecular dynamics calculations show that ethanol and isopropanol displace water from the calcite [ 10 1 ¯ 4 ] surface forming an immobile, ordered, and hydrophobic layer, while acetone and water form a mixed, dynamic environment. In experimental trials, a continuous (yet cracked) layer of carbonate hydroxyapatite is formed after 24 h, with all organic additives improving the final coating. This result suggests that the interaction of the additive with the marble surface does not play a major role in determining treatment outcomes and other factors should be investigated for the design of improved treatments. [ABSTRACT FROM AUTHOR]

Calcium carbonate and cadmium-rich fluid interactions have been studied at the nano and microscale with fluid flow and static fluid conditions for three forms of CaCO 3 : calcite in single crystals of Iceland Spar, calcite in a polycrystalline Carrara marble, and aragonite single crystals. Atomic Force Microscopy (AFM) showed the nanoscale effect of cadmium on CaCO 3 dissolution and growth under flow-through conditions at ambient temperature, with the modification of calcite dissolution behaviour and simultaneous precipitation of a Cd-rich phase on all the different samples. Hydrothermal experiments at 200 °C revealed that the reactivity of single calcite crystals is passivated by epitaxial growth of the less soluble Cd-rich endmember of the (Ca,Cd)CO 3 solid-solution on the sample surface due to the similar crystallographic structures of calcite and otavite (CdCO 3). Conversely, the presence of grain boundaries in Carrara marble or the change of crystallographic structure and reaction-induced fracturing in aragonite allowed, to some extent, the pseudomorphic replacement of Carrara marble and aragonite samples by a porous (Ca,Cd)CO 3 solid-solution phase of variable composition. These phenomena have been observed in solutions undersaturated with respect to all solid phases and are the result of an interface-coupled dissolution-precipitation mechanism where the dissolving CaCO 3 provides ions to supersaturate the mineral-fluid interfacial layer, leading to the precipitation of a Cd-containing phase on the samples' surfaces. This coupled dissolution-precipitation mechanism could potentially be used as a remediation process to sequester cadmium from contaminated effluents. • Cadmium modifies CaCO 3 dissolution and growth under flow-through conditions at ambient temperature. • Cadmium in solution passivates calcite single crystal on long term exposure. • The presence of fluid pathways/change of crystallographic structure allows the replacement of CaCO 3 by a (Ca,Cd)CO 3 phase. • CaCO 3 as limestone, marble or aragonite can be used to sequester Cd in solutions. [ABSTRACT FROM AUTHOR]

Micro-cracks induced by the coring process in rock samples retrieved from high in situ stress conditions may seriously influence the evaluation of rock properties. This paper presents work performed to study the coring damage mechanism of marble samples containing a kind of inclined grey (or brown) ribbon-like stripes, whose mineral components are calcite and dolomite. These samples were obtained from the Jin-ping Second Stage Hydropower Station (JPII) in China, and the coring site is located in the strata of the 5th layer of the Yan-tang group marble in the Middle Triassic system (T). A special stress-relief coring scheme was carried out to collect rock samples under different stress levels at one position, then the coring damage in these samples was examined by sonic wave testing and acoustic emission monitoring under uniaxial loading conditions, and a numerical simulation was also conducted to investigate the stress path experienced by a rock core during sampling. The results indicate that for the specific Jin-ping Yan-tang group marble (T) sample, the coring damage can be attributed to two kinds of micro-cracks: horizontal micro-cracks induced by stress redistribution, and vertical or sub-vertical micro-cracks mainly derived along the special rock structure. The horizontal cracks, generated by the tensile stress induced during coring, are mostly trans-granular ones, and can be regarded as the main reason for coring damage. In contrast, the vertical (or sub-vertical) micro-cracks are mainly caused by the combined effect of coring-induced high deviatoric stress and the inclined grey-brown ribbons, and it usually occurs along grain boundaries. At a relatively low stress level, the shear failure may preferentially occur along special rock structures. However, the impact of the micro-structure on cracking reduces significantly with the increase of stress level, and then the induced tensile stress may become the dominant factor leading to horizontal cracks or disking. [ABSTRACT FROM AUTHOR]

Dolomitic marble on the island of Naxos was deformed at variable temperatures ranging from 390 °C to >700 °C. Microstructural investigations indicate two end-member of deformation mechanisms: (1) Diffusion creep processes associated with small grain sizes and weak or no CPO ( c rystallographic p referred o rientation), whereas (2) dislocation creep processes are related with larger grain sizes and strong CPO. The change between these mechanisms depends on grain size and temperature. Therefore, sample with dislocation and diffusion creep microstructures and CPO occur at intermediate temperatures in relative pure dolomite samples. The measured dolomite grain size ranges from 3 to 940 μm. Grain sizes at T max >450 °C show an Arrhenius type evolution reflecting the stabilized grain size in deformed and relative pure dolomite. The stabilized grain size is five times smaller than that of calcite at the same temperature and shows the same Arrhenius-type evolution. In addition, the effect of second phase particle influences the grain size evolution, comparable with calcite. Calcite/dolomite mixtures are also characterized by the same difference in grain size, but recrystallization mechanism including chemical recrystallization induced by deformation may contribute to apparent non-temperature equilibrated Mg-content in calcite. [ABSTRACT FROM AUTHOR]

Extreme strain localization occurred in the centre of the cross-cutting element of a flanking structure in almost pure calcite marbles from Syros, Greece. At the maximum displacement of 120 cm along the cross-cutting element, evidence of grain size sensitive deformation mechanisms can be found in the ultramylonitic marbles, which are characterized by (1) an extremely small grain size (~3 µm), (2) grain boundary triple junctions with nearly 120° angles, (3) a weak crystallographic preferred orientation with very low texture index (J = 1:4), (4) a random misorientation angle distribution curve and (5) the presence of small cavities. Using transmission electron microscopy, a deformation sequence is observed comprising recrystallization dominantly by bulging, resulting in the development of the fine-grained ultramylonite followed by the development of a high dislocation density (~1013 m-2) with ongoing deformation of the fine-grained ultramylonite. The arrangement of dislocations in the extremely fine-grain-sized calcite differs from microstructures created by classical dislocation creep mediated by combined glide and thermally activated climb. Instead, it exhibits extensive glide and dislocation networks characteristic of recovery accommodated by cross-slip and network-assisted dislocation movement without formation of idealized subgrain walls. The enabling of grain boundary sliding to dislocation activity is deemed central to initiating and sustaining strain softening and is argued to be an important strain localization process in calcite rocks, even at a high strain rate (~10-9 s-1) and low temperature (300 °C). [ABSTRACT FROM AUTHOR]

Samples of marble from Chillagoe, North Queensland have been analysed using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. Different types of marble were studied including soft white marble, hard white marble and a black marble. In this work, we try to ascertain why the black marble has this colour. Chemical analyses provide evidence for the presence of minerals other calcite in the marble, including the pyrite mineral. Some of these chemical analyses correspond to pyrite minerals in the black marble. The Raman spectra of these crystals were obtained and the Raman spectrum corresponds to that of pyrite from the RRUFF data base. The combination of SEM with EDS and Raman spectroscopy enables the characterisation of the mineral pyrite in Chillagoe black marble. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Marble, a stone composed of the mineral calcite, is subject to chemically induced weathering in nature due to its relatively high dissolution rate in acid rain. To protect monuments and sculpture from corrosion, we are investigating the application of thin layers of hydroxyapatite (HAP) onto marble. The motivation for using HAP is its low dissolution rate and crystal and lattice compatibility with calcite. A mild, wet chemical synthesis route, in which diammonium hydrogen phosphate salt was reacted with marble, alone and with cationic and anionic precursors under different reaction conditions, was used to produce inorganic HAP layers on marble. Nucleation and growth on the calcite substrate was studied, as well as metastable phase evolution, using scanning electron microscopy, grazing incidence X-ray diffraction, and atomic force microscopy. Film nucleation was enhanced by surface roughness. The rate of nucleation and the growth rate of the film increased with cationic (calcium) and anionic (carbonate) precursor additions. Calcium additions also influenced phase formation, introducing a metastable phase (octacalcium phosphate) and a different phase evolution sequence. [ABSTRACT FROM AUTHOR]

It is generally accepted that grain boundary sliding (GBS) is the dominant deformation mechanism in fine-grained strain localization zones. However, the lifetime of GBS during deformation in monomineralic rocks is hotly debated, as grain growth may inhibit the operation of GBS. In this contribution, recrystallized matrix grains in calcite marbles from the Jinzhou detachment fault zone at the middle crustal level, Liaodong Peninsula, Northeast China, show clear evidence of GBS, e.g., 1) fine grains with sizes of 5–30 μm, nearly equant grain shapes and slightly curved grain boundaries, 2) rare evidence for intracrystalline deformation, 3) existence of four-grain junctions and aligned straight grain boundaries, and 4) weak crystallographic preferred orientations. The existence of high misorientation zones along the margins of the matrix grains, especially at their triple junctions, and differences in cathodoluminescence (CL) characteristics between rims and cores of the grains indicate simultaneous accommodation of GBS by dislocation motion and grain boundary diffusion. The different CL characteristics between rims and cores of calcite matrix grains and the presence of calcite-filled cracks imply fluid activity during deformation. Fluids could dramatically enhance GBS by promoting dislocation motion and grain boundary diffusion. Additionally, the nucleation of fine grains by dynamic recrystallization and cavitation-sealing processes during GBS guaranteed the maintenance of GBS. At the same time, the occurrence of micropores and the existence of second phases also inhibit grain growth. These features make GBS the dominant deformation mechanism in naturally deformed marbles in the middle-upper crust. • Grain boundary sliding (GBS) is the dominant deformation mechanism in calcite matrix. • Fine calcite grains were continuously formed by SGR and cavitation-sealing process during GBS. • Grain growth is inhibited by drag force of second phase and pores during GBS. • Fluid activities significantly promote GBS. [ABSTRACT FROM AUTHOR]

Marble slabs are frequently used as façade panels to externally cover buildings. In some cases a bowing of such façade panels after a certain time of environmental exposure is experienced. The bowing is generally accompanied by a reduction of strength which increases with increasing degree of bowing. In the present paper, a theoretical model to calculate the progressive bowing of marble slabs submitted to temperature cycles is applied to a specific Carrara marble sample. The marble is investigated by a microscopic analysis of thin sections cut along three orthogonal directions. The digital photographs are treated by an image analysis code which is capable of extracting grain size and shape distributions. In this way the anisotropic microstructure of the marble is quantified and taken into account in the numerical analyses. The influence of size distribution of grains as well as of their distribution of optic axis orientation on the slab bowing is discussed with the attempt of offering a quantitative tool for a better understanding of in situ bowing measurements. [ABSTRACT FROM AUTHOR]

Rutile, titanite, and zircon formed as relatively coarse-grained accessory minerals in several samples of high-grade calcite-dolomite marble with an early ultrahigh-pressure history. These minerals decomposed to a texturally complex set of secondary minerals during subsequent stages of retrograde metamorphism. The reactions involve several generations of geikielite-ilmenite as well as zirconolite [(Ca,Th,U)Zr(Ti,Fe,Nb,Ta)2O7], kassite/cafetite [CaTi2O4(OH)2/CaTi2O5·H2O], Ti-bearing humite group minerals, thorianite, and sometimes euxenite [(Ca,U,Th,REE)(Nb,Ta,Ti)2(O,OH)6]. Stable coexistence of zircon and olivine is observed and stably coexisting titanite with olivine and/or humite-group minerals is reported here for the first time outside of carbonatites, kimberlites, or lamprophyres. Petrogenetic grids constructed for Ti- and Zr-bearing olivine/antigorite-saturated calcite-dolomite marbles show that geikielite is stable at highest pressures, followed by titanite and rutile, and that baddeleyite + diopside replaces zircon + calcite to higher pressures. The observed reaction textures are consistent with an earlier derived P-T path for the Kimi Complex. They corroborate a period of heating during decompression from 25 to 20 kbar and ca. 800 °C, where the assemblage olivine-diopside-spinelrutile- zircon formed. This assemblage partially re-equilibrated during subsequent decompression and cooling, thus forming the observed reaction textures. Even though no memory of the UHP path is preserved in the accessory minerals, their reaction relationships turn out to be potentially very useful for geothermobarometry over a large range of metamorphic conditions. [ABSTRACT FROM AUTHOR]

A kinetic and thermodynamic study of selected calcite marble samples from Lesser Himalayas has been performed using thermogravimetric and differential thermal analyses at heating rates of $$10\,^{\circ }\mathrm{C}\,{\cdot }\min ^{-1}$$ and $$30\,^{\circ }\mathrm{C}\,{\cdot }\min ^{-1}$$ . The minero-petrography of calcite grains, phase analysis, chemical analysis, and minor impurities determination were carried out using thin-section polarized light microscopy, X-ray diffraction, X-ray fluorescence, and electron microprobe analysis, respectively. The calcite content of the investigated marble samples varied from 97.50 mass% to 98.70 mass%. The activation energy, $$E_\mathrm{a}$$ , for the decomposition process increased from $$158.6\,\mathrm{kJ}\,{\cdot }\mathrm{mol}^{-1}$$ to $$179.4\,\mathrm{kJ}\,{\cdot }\,\mathrm{mol}^{-1}$$ and from $$214.1\,\mathrm{kJ}\,{\cdot }\, \mathrm{mol}^{-1}$$ to $$232.8\,\mathrm{kJ}\,{\cdot }\, \mathrm{mol}^{-1}$$ for heating rates of $$10\,^{\circ }\mathrm{C}\,{\cdot }\, \min ^{-1}$$ and $$30\,^{\circ }\mathrm{C}\,{\cdot }\, \min ^{-1}$$ , respectively, with decreasing calcite content. The activation energy values obtained in the present study were in good agreement with previous studies. [ABSTRACT FROM AUTHOR]

Production of concrete, asphalt, and fill material sector in areas such as at the beginning of the raw materials used in the aggregate are the most important. Increasingly rapid development of industrialization increased the value of aggregate. According to 2011 market share of aggregate world-wide reach approximately € 90 billion in oil, natural gas and coal took place within the first 5. Thanks to marble cutting process evolving technology the last 25 years, production had a large volume of marble quarries in the region. The estimated is from Iscehisar marble quarry about annual 500.000 tons of marble waste. Marbles in the region, respectively, from bottom to top, Tigerskin, Grey, Sugar, White and Violet are represented as. Marbles are formed as one of the largest in the second lens. 30 enterprises operating in the marble quarry is located in this area. There are 400 marble factories near the center and around Iscehisar. Both the marble quarries of marble processing facilities and the waste is a major concern for the region. A detailed survey was conducted within the scope of the study. As a result of working in marble wastes and on the evaluation of Iscehisar important data is gathered. [ABSTRACT FROM AUTHOR]