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Fulgurites are a naturally occurring glass formed when sand, rock, or soil is struck by atmospheric electrical discharges (lightning). The aim of this paper is to provide insights into the conditions occurring in rocks during the lightning strike. Rock fulgurites collected from Mt. Mottarone, Baveno (Piedmont, Italy) have been investigated to assess the mineralogical and compositional changes occurring in granite due to a lightning strike. X-ray powder diffraction showed that the samples represent the dominant granitic rock type of the Baveno massif, the so-called “Pink Baveno.” Fulgurite coats the surface of the granite as a brown-black, glassy to very fine-grained porous layer. Powder diffraction data for the fulgurite reveal the presence of cristobalite and quartz crystals in a glass matrix, suggesting that temperature exceeded ~1700 °C at near atmospheric conditions, assuming thermodynamic equilibrium. Electron probe microanalysis of the glass revealed that it is mainly composed of SiO 2 and Al 2 O 3 and that it has a porosity of 5–7 area% in the studied zones. The presence of the amorphous phase indicates that the abrupt electrical (Joule) heating of the rock surface yielded high temperatures, producing a thin melt layer on the surface, which then cooled adiabatically. Idealized physical model was developed to simulate the effects of Joule heating and subsequent thermal conduction close to the rock surface during and after a lightning strike. The quantity of organic matter in the glass, obtained via Elemental Analyzer, suggests that rapid quenching of the melt trapped NO x and CO x gases produced during heating. Raman spectroscopy revealed the presence of polyaromatic hydrocarbon molecules, which, combined with the Elemental Analyzer data, suggest that organic matter was pyrolyzed at around 300–350 °C and then trapped in the glass matrix of the studied rock fulgurites.

By applying the method of chemical shifts of the uranium L α1 and L β1 X-ray emission lines, the oxidation state of U has been determined in select samples of microlite and monazite. From the relative contents of U4+, U5+, and U6+ species, the oxygen coefficients have been calculated as a characteristic of U-oxidation rate. It is shown that the oxidation state of U is higher in the studied microlite than in monazite. Possible mechanisms of U oxidation in these two types of minerals are discussed, and it appears that the crystal structure of monazite plays an important role in stabilizing the U redox state. Spontaneous purification of the monazite structure from alien atoms, including U, may be possible via recrystallization of the α-recoil tracks. An explanation is suggested for intensive U oxidation in microlite and in other minerals of the pyrochlore group.

Book Review: Amazonite: Mineralogy, Crystal Chemistry, and Typomorphism. (2016) By Mikhail Ostrooumov. Elsevier. ISBN: 978-0-1280-3721-8, 228 p. $120. This new book is a translation of the original Russian language edition, which the author Mikhail Ostrooumov published in 2008 together with his colleagues A. Platonov and V. Popov (Ostrooumov et al. 2008). The Russian version was based on a precursor volume, which became a bibliographic rarity shortly after its publication in 1989 (Vochmentzev et al. 1989). The 2008 version, and the English translation reviewed here, expand upon the 1989 edition of the monograph by including subsequent research results, making corrections, and by adding more recent references. The book is dedicated to amazonite, a variety of potassium feldspar that, due to its distinct colors, has intrigued humans since antiquity, as has been noted by the renowned mineralogist Alexander Fersman. The recent discovery of Neolithic, and possibly even older, amazonite beads in archeological sites in Israel (Bar-Yosef Mayer and Porat 2008) highlights the fascination with this green, greenish-blue, or blue mineral. At that time (10 500–8200 B.P.), i.e., during the transition from hunting and gathering to agriculture in the Near East, the earliest farmers had to make great efforts at obtaining the raw materials from far-away places. It is clear why this variety of potassium feldspar presents …

Fly ash from a coal-fired power plant was investigated to obtain detailed information on its physical and chemical properties, and to gain an understanding of potential environmental and health impacts associated with itsdisposal in landfills. The studied material was produced through combustion of Illinois Basin coal and trapped within the power plant by an electrostatic precipitator. It is a fine-grained, low-Ca fly ash containing primarily SiO 2 , Al 2 O 3 , and Fe 2 O 3 , and is enriched in many toxic elements (e,g., Be, Zn, As, Cd, Tl, Pb, and U) by a factor of up to 30 relative to coal. The ash consists of mainly hematite, magnetite, mullite, quartz, and amorphous material. These constituents occur mostly as spherical particles with diameters of less than 13 μm. We examined the physical, chemical, and structural characteristics of individual fly ash particles by scanning and transmission electron microscopy and electron probe microanalysis. The results demonstrate that, with the exception of complex plerospheres, individual particles are chemically fairly homogeneous, but a pronounced compositional variation exists among particles with similar physical and structural attributes. Electron microprobe data document that several trace elements, including U, are partitioned into the Fe-rich particles. Transmission electron microscopy revealed that various types of small (

Small syngenetic exhalative Fe-Mn deposits embedded in Triassic marbles of the Suretta, Starlera, and Schams nappes (Eastern Swiss Alps) were subjected to a Tertiary regional metamorphism under blueschist- to greenschist-facies conditions. In one of the deposits (at Fianel, Val Ferrera), this polyphase metamorphism led to the formation of quartz1dolomite veinlets containing beryl, scheelite-powellite, paraniite-(Y), monazite- (Ce), fluorapatite, bergslagite, fluor-romeite, and antimonian betafite; these veinlets crosscut dolomite breccia lenses that are embedded in hematite-quartz-carbonate ores. Scheelite- powellite displays a continuous range of compositions between 28 and 70 mol% CaMoO4; its As2O5 contents range from 0.73 to 3.96 wt%, and are positively correlated with the Y2O3 contents that vary between 0.33 and 2.47 wt%. The scheelite-powellite grains display a two-stage chemical zoning: stage A generally produced a core and a rim that, relative to the core, is richer in W, As, and Y. During the second stage (stage B), W-rich scheelite- powellite replaces stage-A grains along fractures and rims. Crystals of paraniite-(Y), ide- ally (CaWO4)2·YAsO4, occur as small inclusions (51 mm) in stage-B scheelite-powellite. The Fianel deposit is only the second locality where paraniite-(Y) has been reported. The paraniite-(Y) from Fianel displays, like the type material, no polysomatic stacking fault in the scheelite-YAsO4 layering. At Fianel, paraniite-(Y) is characterized by elevated Mo contents, and seems to have crystallized under influence of W- and LREE-rich fluids during stage B, i.e., during the metasomatic replacement of Y- and As-rich scheelite-powellite produced in stage A.

The compositional evolution of tourmaline from diagenetic to lower amphibolite-facies conditions was investigated in two metasedimentary units (redbed and black shale formations) along a traverse across the Central Alps. With increasing metamorphism, three distinct rim zones grew around detrital tourmaline cores, simultaneously with the development of prismatic neoblasts. Detrital cores and all successive rim zones are preserved in the amphibolite-facies rocks. As indicated by whole-rock data, the B required for tourmaline growth was released from illite and muscovite and was not introduced from external sources. The studied samples of tourmaline exhibit compositional polarity, i.e., their compositions are different at the opposite ends of the c axis. The compositional difference between the two poles can be expressed by the substitutions Na + Mg ;= 0 + Al and 2Al ;= Ti + Mg, with the positive pole always richer in Al and having more X-site vacancies. Both chemical and optical polar effects are most pronounced in the internal rim zones and become less prominent toward the external zones. The systematic prograde compositional trends are depicted in a vector space for Li-poor tourmaline. At low-grade conditions, the tourmaline composition is clearly controlled by the host-rock composition, but with increasing metamorphic grade the compositions of tourmaline from a variety of rocks converge. The data show that in the Central Alps, increasing metamorphic grade is reflected by increases in Ca/(Ca + Na) and Mg/(Mg + FeH), a decrease in Fe3+, and an increase in the occupancy of the X site of tourmaline.