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Sphene (CaTiSiO5, i.e. CaO·TiO2·SiO2) ceramics were successfully developed via the polymer derived ceramics route, starting from a commercial silicone containing specific oxide fillers. The approach allowed the combination of synthesis, in conditions of high phase purity, and advanced manufacturing. In particular, the adopted starting materials enabled an easy preparation of pastes, to be used for direct ink writing (DIW) of three-dimensional reticulated scaffolds. Sphene scaffolds, after firing at 1300 °C, were always regular and crack-free, despite changes in the line spacing, resulting in variable porosity (from ≈ 59 to 74 %), and exhibited a compressive strength from 3.9 to 12.7 MPa. The porosity was actually hierarchical, considering the formation of ‘spongy’ struts. In vitro tests, with increasing immersion time in SBF solution, confirmed the bioactivity, combined with a quite slow ion release, useful to maintain the pH value at nearly physiological values. Additional biological tests, consisting of the seeding of scaffold with normal human adult dermal fibroblasts, showed adequate cell viability and no toxicity effect.

Sphene based glass-ceramics (CaTiSiO5), an excellent candidate for a host lattice of ceramic materials and for nuclear waste immobilization, has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibro-milling for homogenization. Starting powders were melted at 1400°C for 2 h, cooled to room temperature, grounded again, then crystallized by thermal treatment yielding a sphene glass-ceramic. The evolution of the phase composition during thermal treatment was investigated by X-ray powder diffraction (XRPD), FT-IR, Raman and thermal analyses (TG-DTA). Pure synthetic single phase sphene was formed at 800°C for 4 h, even it is very hard to obtain monophase powder at such low temperature. Powder morphology was analyzed by scanning electron microscopy (SEM). [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45012]

Titanite is an important mineral in petrochronology studies. Understanding chemical signatures of titanite from different environments can provide significant data in unraveling the complex histories recorded in their textures and compositions. Using a database of over 8500 titanite analyses from both the literature (3829) and our own data (4900), we found that the ratio of Fe/Al is useful for separating igneous titanite (Fe/Al is typically close to 1:1 and almost always > 1:2) from metamorphic titanite (Fe/Al ratio is < 1:2) with few exceptions. Volcanic titanite grains can also be separated from plutonic titanite grains due to their shorter crystallization histories with compositions clustered more tightly in terms of Fe, Al, and F. Compositions of titanite from plutonic rocks often have later metamorphic or hydrothermal overgrowths that are not found on volcanic titanite. Fe/Al ratios in titanite from silica-undersaturated volcanic and plutonic rocks are typically > 1:2 and include titanite with the highest Fe/Al ratios. Although they overlap the field for normal igneous titanite, other elements (particularly high levels of Nb and low levels of Y) allow them to be separated. In most metamorphic rocks, the Fe/Al ratio is < 1:2 except for a few metamorphic titanite grains that formed in mafic rocks. Titanite from ultrahigh pressure metamorphic rocks (eclogite facies) tend to have the lowest Fe/Al ratios, typically < 1:8. Titanite from hydrothermal and pegmatitic environments scatter widely in terms of Fe/Al even within single grains due to crystallization from fluids with highly variable compositions. Charge balancing in metamorphic, hydrothermal, and pegmatitic titanite due to Fe+3 and Al+3 substitution into the Ti+4 site is largely accomplished by the coupled substitution of F− for O−2. However, in volcanic and plutonic titanite, the charge imbalance due to Fe+3 and Al+3 substitution appears to be mainly coupled with REE+3 or Y+3 substitution into the Ca+2 site with a lesser contribution from F−.

Silica-based ceramics have been proposed for coating purposes to enhance dental and orthopedic titanium (Ti) implant bioactivity. The aim of this study was to investigate the influence of sphene-based bioceramic (CaO.TiO2.SiO2) coatings on implant osseointegration in vivo. Sphene coatings were obtained from preceramic polymers and nano-sized active precursors and deposited by an automatic airbrush. Twenty customized Ti implants, ten sphene-coated and ten uncoated rough implants were implanted into the proximal femurs of ten Sprague-Dawley rats. Overall, cortical and cancellous bone-to-implant contact (BIC) were determined using micro-computed tomography (micro-CT) at 14 and 28 days. Moreover, peri-implant bone healing was histologically and histomorphometrically evaluated. The white blood cell count in the synovial fluid of the knee joints, if present, was also assessed. No difference in the BIC values was observed between the sphene-coated and uncoated implants, overall and in the two bone compartments (p &gt, 0.05). Delamination of the coating occurred in three cases. Consistently with micro-CT data, the histological evaluation revealed no differences between the two groups. In addition, no synovial fluid could be collected on the test side, thus confirming sphene biocompatibility. In conclusion, sphene coating was found to be a suitable material for biomedical applications. Further studies are needed to improve coating adhesion to the implants.

Over the last few decades, due to the aging of the population, prolonged life expectancy and increased demand for esthetic dental procedures, there is an increasing request for dental implant treatment for the replacement of missing teeth. In addition, in presence of an inadequate amount of bone for implant positioning, bone regeneration procedures are required. Among various strategies, which are currently being investigated, synthetic biocompatible three-dimensional structures, known as “scaffolds”, produced using different additive manufacturing technologies are attracting growing attention for use in bone tissue regeneration, as personalized bone scaffolds can be designed to fit specific bone defects. Successful use of bioactive ceramics, as coating materials for dental implants as well as bone substitutes, has been reported. In particular, sintered hydroxyapatite (HA) has been extensively employed in clinical dental practice. However, its low fracture toughness and the occurrence of delamination at the interface with titanium substrates have significantly limited the scope of clinical applications. More recently, a new category of bioactive ceramics, i.e. silicate-based ceramics, has received great attention, due to their remarkable bioactivity and good mechanical properties. The primary aim of the current project is to develop and test in vitro and in vivo a specific bioactive silicate-based ceramic, sphene (CaTiSiO5), as coating material for dental implants. Sphene coatings will be prepared using a preceramic polymer containing nanosized active fillers as precursors for the formation of the desired ceramic phase. Coating will be applied by airbrushing, and the samples will undergo heat treatment, in order to transform the precursors into a ceramic coating. Once the sphene-coated implants will be prepared, they will be fully characterized in terms of microstructure analysis, crystalline phase assemblage, physicochemical properties, effect on mesenchymal stem cell behavior in vitro, and, finally, osseointegration in a rat model. Secondary aim of this project consists in the production and characterization of sphene ceramic scaffolds to be utilized as bone substitutes for bone tissue regeneration. These scaffolds will be fabricated by direct ink writing using a preceramic polymer and nano sized active fillers. The samples will be then characterized, and a particular attention will be given to investigating in vitro cytocompatibility and osteoconductive properties, prior to in vivo study using rat critical size calvarial defect model.

Surface modification of titanium-based implants has been extensively researched as an effective tool to generate a bioactive surface that helps to create a new bone and forms a natural bond at the interface between the implants and surrounding bone tissues. The present research is focused on the development of a new methodology to obtain sphene (CaTiSiO 5 ) biocoatings on titanium substrates. Based on previous results, where sphene coatings were obtained by a manual airbrush, the coating system was improved in order to have a full control of the process in terms of uniform morphology of the biocoating. The effectiveness of the coating system and deposition process is supported by microscopic analysis of the produced coatings, by surface roughness measurements of uncoated and coated substrates, and estimation of the adhesion strength between the coatings and the substrate. The results showed that the coatings had crack-free homogenous surfaces with ideal characteristics for orthopedic and dental implants in terms of adhesion strength and surface roughness.

Rods of commercially pure titanium were machined using standard oil-based emulsion and cryogenic cooling, and were then coated with sphene (CaTiSiO5) bioceramic by spray coating using an automatic airbrush. The sphene bioceramic was synthesized in-situ starting from a suspension of polysiloxane that used as SiO2 precursor, CaCO3 and TiO2 nanoparticles. The suspension was deposited on the machined substrates, which were heat treated up to 950 °C in order to promote the formation of sphene ceramic. The produced coated prototypes were characterized to evaluate the effect of the machining conditions on surface roughness and microstructure of the substrate, and thereby their effect on coating adhesion. Nanoindentation tests were employed to determine the hardness and elastic modulus of the coating through its thickness. Results showed that the reduced amount of defects on the surface of the cryo-machined substrates, contributed to increase the hardness, elastic modulus and adhesion strength of the coating-substrate interfaces compared to standard machined samples, therefore improving adhesion of the coating to the underlying substrate.

Titanium implant surface modifications have been widely investigated to favor the process of osseointegration. The present work aimed to evaluate the effect of sphene (CaTiSiO5) biocoating, on titanium substrates, on the in vitro osteogenic differentiation of Human Adipose-Derived Stem Cells (hADSCs). Sphene bioceramic coatings were prepared using preceramic polymers and nano-sized active fillers and deposited by spray coating. Scanning Electron Microscopy (SEM) analysis, surface roughness measurements and X-ray diffraction analysis were performed. The chemical stability of the coatings in Tris-HCl solution was investigated. In vitro studies were performed by means of proliferation test of hADSCs seeded on coated and uncoated samples after 21 days. Methyl Thiazolyl-Tetrazolium (MTT) test and immunofluorescent staining with phalloidin confirmed the in vitro biocompatibility of both substrates. In vitro osteogenic differentiation of the cells was evaluated using Alizarin Red S staining and quantification assay and real-time PCR (Polymerase Chain Reaction). When hADSCs were cultured in the presence of Osteogenic Differentiation Medium, a significantly higher accumulation of calcium deposits onto the sphene-coated surfaces than on uncoated controls was detected. Osteogenic differentiation on both samples was confirmed by PCR. The proposed coating seems to be promising for dental and orthopedic implants, in terms of composition and deposition technology.

A large number of unexploited low-grade vanadium-titanium magnetite deposits have been found in the Chao-yang area of China in recent years. The reserves are estimated at more than 20 billion tons. A mineralogical study of raw sample indicated that it was a typical low-grade vanadium-titanium magnetite ore with weathering. Most of vanadium-titanium magnetite was replaced by martite and sphene, which would affect the recovery of valuable elements. The intergrowth relationship between vanadium-titanium magnetite and sphene was very complex, and the grain size of sphene was generally fine, and could not be completely liberated even by fine grinding, whereas the content of vanadium and titanium in sphene was higher than that in vanadium-titanium magnetite, resulting in vanadium-titanium magnetite concentrates with characteristics of high vanadium and titanium content. A magnetic separation process was investigated for the pre-concentration of low-grade vanadium-titanium magnetite ore. The results showed that 73.52% of feed ore were directly discarded for reducing the processing capacity of follow-up processing. A vanadium-titanium magnetite concentrate with 1.14% V2O5, 22.22% TiO2, 42.51% Fe and a rough concentrate of ilmenite with 16.05% TiO2, 20.77% Fe were obtained from low-grade vanadium-titanium magnetite ore which contains 0.050% V2O5, 1.67% TiO2 and 8.53% Fe.

Sphene (CaTiSiO5), a calcium titanosilicate ceramic has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibro-milling for homogenization and activation of precursors. During the high-pressure and high-temperature synthesis (HPS) process at 4 GPa and 1,200 °C, sphene undergoes into phase transition, from room-temperature phase P21 /a to high-temperature phase A2/a. Evidence of that structural phase transition is given in this paper using infrared, Raman spectroscopy and X-ray powder diffraction. Rietveld refinement was employed to get the structural information of the synthesized powder. The most important structural change due to phase transition, the disappearance of the characteristic out-of-center distortion of the Ti atom and moving to the center of octahedra, was confirmed. HPS is an effective method for producing full-dense ceramics without any additives. Reduction of particle size occurred during high-pressure compaction. Microstructure and particle size of both phases were analyzed by scanning electron microscopy.

Mechanical activation of precursors has been used for the preparation of Cr-doped sphene ceramic pigments (CaTi1-yCrySiO5). Ceramic material has been prepared from a powder mixture of CaCO3, TiO2, SiO2 and Cr(NO3)center dot 9H(2)O using vibro-milling for homogenization and activation of precursors. The mechanochemical process initially yielded amorphous powders, which on further calcination, crystallized to yield Cr-doped sphene ceramic pigment. Phase evolution in CaTi1-yCrySiO5 composition with thermal treatment was investigated by X-ray powder diffraction (XRPD). Texture properties and particle size distribution were analyzed by scanning electron microscopy (SEM) and laser diffraction, respectively. UV/Vis reflectance spectra are used to determinate the behavior of the chromium ion. The color efficiency of pigments was evaluated by colorimetric analysis (CIE L * a * b system). Photoluminescence measurements were also performed. (c) 2013 Elsevier B.V. All rights reserved.

Sphene (CaTiSiO5), a calcium titanosilicate ceramic has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibromilling for homogenization and activation of precursors. The mechanochemical process initially yielded amorphous powders, which on further calcination, crystallized to yield sphene ceramic. The evolution of the phase composition with thermal treatment was investigated by X-ray powder diffraction (XRPD). Powder morphology and particle size distribution were analyzed by scanning electron microscopy (SEM) and laser diffraction, respectively. Rietveld refinement was employed to get the structural information of the synthesized powder. Densification and microstructure evolution was determined by means of density and scanning electron microscopy (SEM). The most favorable conditions for mechanical activation and synthesis of sphene based ceramic material are reported. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

White glazes opacified by sphene, based on the system SiO2-CaO-TiO2, are an alternative to the glazes in which the opacifying phase is zircon. However, it has been observed that this type of glaze displays photochromism (reversible change of colour after exposure to a light source), involving the appearance of a yellowish shade after the glaze has been subjected to sunlight for several hours, which then disappears after a few days. This effect has led to limited use of this type of glaze. In this study, a method of quantifying the photochromic effect by means of a UV light source is established. The microstructural characterisation of glazes with a pronounced tendency to display a photochromic effect has allowed the possible causes of the photochromic effect to be determined. Finally, a series of tests have been conducted that show that the photochromic effect is related to the impurities present in the glaze, as well as to the type and quantity of crystalline phases contained in the glaze.Los vidriados blancos opacificados por esfena, basados en el sistema SiO2-CaO-TiO2, son una alternativa a los vidriados en los que la fase opacificante es el circón. Sin embargo, se ha observado que este tipo de vidriados presentan fotocromismo (cambio de color reversible tras la exposición a una fuente de luz), el cual consiste en la aparición de una tonalidad amarillenta tras someter el vidriado a la luz solar durante varias horas, que desaparece al cabo de varios días. Este efecto hace que la utilización de este tipo de vidriados no se haya generalizado. En el presente trabajo se establece un método para la cuantificación del efecto fotocrómico mediante el uso de una fuente de luz ultravioleta. La caracterización microestructural de vidriados con distinta tendencia a presentar el efecto fotocrómico ha permitido establecer las posibles causas que provocan el efecto fotocrómico. Finalmente, se han realizado una serie de ensayos que ponen de manifiesto que el efecto fotocrómico está relacionado con las impurezas presentes en el vidriado así como con el tipo y cantidad de fases cristalinas presentes en su seno.

Lesnica river deposits consist of a large number of minerals of different grain sizes including sphene. Since it is very difficult to obtain pure monophase titanite by different synthetic routes (sol-gel, coprecipitation, combustion, spray pyrolysis and hydrothermal method), the aim of this work was to study the structure of the sphene from the Lesnica river deposits and possibility of using it as a natural precursor for CaO-TiO2-SiO2 based ceramics. The sphene from Lesnica was analyzed by different methods: tristimulus colorimetry, infrared spectroscopy, electron microprobe and X-ray single crystal diffraction. It was confirmed that Al, Fe, Mn and P are present in the sphene structure and proposed that corresponding structural formula could be: (Ca2+1.008 Mn2+0.002)1.010(Ti4+0.901 Fe3+0.033 Al3+0.060 P5+0.001)0.995 Si4+1.024 O2-5.

Hydroxyapatite (HAp) is commonly used to coat titanium alloys (Ti-6Al-4V) for orthopedic implants. However, their poor adhesion strength and insufficient long-term stability limit their application. Novel sphene (CaTiSiO5) ceramics possess excellent chemical stability and cytocompatibility. The aim of this study is to use the novel sphene ceramics as coatings for Ti-6Al-4V. The sol-gel method was used to produce the coatings and the thermal properties, phase composition, microstructure, thickness, surface roughness and adhesion strength of sphene coatings were analyzed by differential thermal analysis-thermal gravity (DTA-TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), atom force microscopy (AFM) and scratch test, respectively. DTA analysis confirmed that the temperature of the sphene phase formation is 875 degrees C and XRD analysis indicated pure sphene coatings were obtained. A uniform structure of the sphene coating was found across the Ti-6Al-4V surface, with a thickness and surface roughness of the coating of about 0.5-1 microm and 0.38 microm, respectively. Sphene-coated Ti-6Al-4V possessed a significantly improved adhesion strength compared to that for HAp coating and their chemical stability was evaluated by testing the profile element distribution and the dissolution kinetics of calcium (Ca) ions after soaking the sphene-coated Ti-6Al-4V in Tris-HCl solution. Sphene coatings had a significantly improved chemical stability compared to the HAp coatings. A layer of apatite formed on the sphene-coated Ti-6Al-4V after they were soaked in simulated body fluids (SBF). Our results indicate that sol-gel coating of novel sphene onto Ti-6Al-4V possessed improved adhesion strength and chemical stability, compared to HAp-coated Ti-6Al-4V prepared under the same conditions, suggesting their potential application as coatings for orthopedic implants.

The ceramic tile industry increasingly commits to modernisation and implementation of new technologies in the decoration process. Current demands of advanced processes in this fi eld, such as rotational decoration, inkjet printing, PVD (physical vapour deposition), laser systems, etc., led to a great interest in developing ceramic pigments with controlled composition and microstructure. These pigments are thermally and mechanically stable in the production cycles, have reproducible and multifunctional properties, and meet ecological and economic demands. The research work in this fi eld made the ceramic sector dynamic and competitive with regard to opening new markets.

The present study is focused on the procedure of spray- and freeze-drying techniques for the preparation of Cr-doped sphene pigments (CaSn0.98Cr0.02 SiO5, CaTi0.98Cr0.02SiO5) from an aqueous solution of precursor salts, followed by calcinations of the resulting powders in absence of additives. The evolution of the present crystalline phases with applied thermal treatments was studied by X-ray powder diffraction and thermal analysis. The powder morphology was analysed by scanning electronic microscopy. The behaviour of the chromium ion was clarified by ultraviolet and visible spectroscopy. The colour efficiency of pigments was evaluated by colourimetric analysis (CIE L*a*b* system). © 2009 Elsevier B.V. All rights reserved.

This preliminary work illustrates the chemical composition of sphene from Variscan tonalites with sphene-centered ocellar texture (Ribadelago pluton, NW Iberian Massif). The ocellar texture is linked with the percolation of a tardimagmatic melt, with trondhjemitic affinities, through an hyperdense crystal mush. Chemical zoning in sphene, revealed by BSE imaging, shows a heterogeneous distribution of heavy trace elements (Nb, Y, Ce and Zr) that depicts concentric, oscillatory, sector and patchy patterns. Application of the Zr-in-sphene thermometer yields a temperature range of 746 to 778 ºC for the crystallization of sphene in the tardimagmatic melt. It also constitutes a minimum temperature estimation for biotite partial destabilization in this lithology

This preliminary work illustrates the chemical composition of sphene from Variscan tonalites with sphene-centered ocellar texture (Ribadelago pluton, NW Iberian Massif). The ocellar texture is linked with the percolation of a tardimagmatic melt, with trondhjemitic affinities, through an hyperdense crystal mush. Chemical zoning in sphene, revealed by BSE imaging, shows a heterogeneous distribution of heavy trace elements (Nb, Y, Ce and Zr) that depicts concentric, oscillatory, sector and patchy patterns. Application of the Zr-in-sphene thermometer yields a temperature range of 746 to 778 ºC for the crystallization of sphene in the tardimagmatic melt. It also constitutes a minimum temperature estimation for biotite partial destabilization in this lithology

The present study is focused on spray and freeze drying procedure for the preparation of Cr-doped sphene pigments (CaSn1-xCrxSiO5, CaTi1-xCrxSiO5) from an aqueous solution of precursor salts plus further calcining the resulting powders. The evolution of the present crystalline phases with applied thermal treatments has been studied by X-Ray Powder Diffraction (XRPD) and thermal analysis (DTA/TG). The powder morphology and chemical composition were analyzed by (SEM). The behaviour of the chromium ion was analyzed by ultraviolet and visible spectroscopy (UV/VIS). The colour efficiency of pigments was evaluated by colorimetric analysis (CIE L*a*b system).

Ceramic pigments with Cr-doped sphene structure (CaSn1-xCrxSiO5, CaTi1-xCrxSiO5) were synthesized by both spray drying an aqueous solution of precursor salts plus further calcining the resulting powders and conventional ceramic method. The thermal evolution of products was studied by X-Ray Powder Diffraction (XRPD). The powder morphology and chemical composition were analyzed by SEM-EDX. The color efficiency of pigments was evaluated by colorimetric analysis (CIELab system). Results showed that the spray drying process decreased the maximum firing temperature and increased the color efficiency of Cr-doped sphene pigments therefore enhancing a higher reactivity of powders compared with the solid state process.

En este artículo se presenta el diseño, la construcción, puesta en marcha y calibración del Sistema Automatizado para la Separación de Minerales Pesados (SASMP) que procesa grandes volúmenes de rocas y sedimentos. Éste tiene por finalidad: hacer una concentración mineral primaria, que posteriormente será refinada y cuyos granos finales de minerales pesados (apatito, circón, esfenas, entre otros) serán utilizados bajo la Técnica del Detector Externo (TDE) para su fechado por el Método de Huellas de Fisión (MHF), utilizado en el Laboratorio de Termocronología de la UCV. Este trabajo, es el resultado de un esfuerzo interdisciplinario entre ingenieros geólogos, matemáticos, ingenieros mecánicos y técnicos en metalurgia, con la finalidad de acelerar los procesos de concentración de minerales pesados para su posterior fechado por el MHF. In this article is presented the design, construction, setting in operation and calibration of the Automated System for the Separation of Heavy Minerals (ASSHM). This equipment processes big volumes of rocks and silts with the purpose of accomplishing a primary mineral concentration thatlater will be refined and whose final grains of heavy minerals (apatite, zircon, sphene, among other) they will be used under the External Detector Technique (EDT) for its dating by the Fission Tracks Dating Method (FTDM) used in the Thermochronology Laboratory of the UCV. This work is the result of an interdisciplinary effort between geologists, mathematicians, mechanical engineers and technicians in metallurgy.

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The Alta stock of granodiorite is closely associated in space and time with many of the Pb, Zn and Ag ore deposits of the Park City-Cottonwood mining area in the central Wasatch Mountains, Utah. The purpose of this study was to determine if fractional crystallization of the Alta magma ultimately resulted in a metal-rich ore-forming fluid. The Alta magma was intruded in two pulses into pre-Triassic sedimentary rocks at a depth of approximately 21,000 feet and at a temperature in excess of 720°C. Detailed study of texture indicates that the first phase of magma solidified with a nonporphyritic texture, crystallizing from the wall progressively toward the center of the stock. The rock at the wall is rich in mafic minerals but grades inward within a few hundred feet to light-gray medium-grained biotite-hornblende granodiorite. Early in the history of the first pulse of magma, convection currents carrying growing crystals of early minerals formed stratified gravity accumulations rich in hornblende, biotite, sphene, magnetite and apatite. These layered masses were subsequently broken and displaced. They now form tabular inclusions of mafic layered granodiorite in the light-gray nonporphyritic granodiorite. At a late stage in the crystallization history, the Alta stock had an essentially solid shell of nonporphyritic granodiorite at least 1200 feet thick that surrounded a partially liquid but semirigid crystal mush at the center of the stock. Structural adjustments at this late stage re sulted in close-space jointing and emplacement of aplite-pegmatite dikes in the nonporphyritic granodiorite shell. After emplacement of the dikes but before the interstitial liquid of the magma at the center of the stock had completely crystallized, the semi-rigid crystal mush and solid shell were intruded by a second pulse of the magma. The distribution of strongly porphyritic texture indicates that loss of volatiles through fractures in the overlying material caused this later phase of the magma to finish crystallization with a fine-grained groundmass. Modal analyses supported by gravimetric chemical analyses show that the porphyritic granodiorite has a slightly more silicic composition than the nonporphyritic granodiorite. The Flagstaff-Emma ore zone in the Little Cottonwood district is on the trend of a westward dike like projection of the porphyritic granodiorite. The fluids that were released during the emplacement of this late phase of the magma conceivably may have been the same fluids that deposited the ore minerals in the Flagstaff-Emma ore zone. In order to determine the trend of the ore-metals during crystallization of the Alta magma, 76 mineral separates of orthoclase, plagioclase, biotite, hornblende, magnetite, sphene, quartz and chlorite were analyzed by the emission spectrographic method for Cu, Pb, Zn, Ag, Co, Ni and Sn. Comparison between samples of the same mineral show that Co and Ni are slightly less abundant and Cu, Pb and Sn are more abundant in the later phases of the Alta igneous suite. No trend is apparent for Ag and Zn. Cu, Co, Ni, Ag and Zn were added to the solid phases of the rock during chloritic alteration. The release of volatiles associated with the late-stage intrusion of porphyritic granodiorite, the structural relation of the adjacent ore deposits to this porphyritic granodiorite and the trend in trace-element abundances suggest that an ore-forming fluid may have been produced at a late stage in the crystallization of the Alta stock.