twenty four samples of xenoliths and country rocks from the 1961 lava flow of calbuco volcano have been studied. fourteen samples have been analyzed for major elements and p, ni, ba, cr, v, zr, sc, y, and sr. five of these samples were further analyzed for sm, nd, sr, and pb isotope ratios. seventeen samples were analyzed under the microscope and three samples were analyzed by microprobe for th...

Polycyclic aromatic hydrocarbons (PAHs) are known to be present in many astrophysical objects and environments, but our understanding of their formation mechanism(s) is far from satisfactory. In this paper, we describe an investigation of the catalytic conversion reaction of acetylene gas to PAHs over pyroxene and alumina. Crystalline silicates such as pyroxenes (with general formula [Mg, Fe]Si...

Introduction: The shergottite basalts, meteorites of Martian origin, contain rare small grains (~10-100 μm diam.) of kaersutite, a Ca-amphibole rich in Al and Ti [1-3]. Kaersutites have been used to estimate the water content of shergottites and the Martian mantle [4]; however, questions remain about the original water content of the amphiboles [5] and if they formed from magma [6]. We investig...

The thermal infrared emissivity spectra of coarse particulate samples of compositions in the pyroxene series display reststrahlen features (absorptions) that distinguish not only orthorhombic from monoclinic structures, but also major endmembers within the two structural groups, as well as minerals within solid solution series. The exact number of reststrahlen features observed and their positi...

The 8–14 µm emission spectra of 12 T Tauri stars in the Taurus/Auriga dark clouds and in the TW Hydrae association obtained with the Infrared Spectro-graph (IRS 1) on board Spitzer are analyzed. Assuming the 10 µm features originate from silicate grains in the optically thin surface layers of T Tauri disks, the 8–14 µm dust emissivity for each object is derived from its Spitzer spectrum. The em...

[1] A series of four synthetic basalts comprising titanomagnetite (Fe3-xTixO4) grains of varied size and titanium content have been produced by a glass-ceramic method. Complementary characterization techniques of X-ray diffractometry, secondary electron microscopy, and transmission electron microscopy (TEM) demonstrate the reaction product composition consisted of mainly Fe3xTixO4, pyroxene hed...

Although visible and near-infrared reflectance spectra contain absorption bands that are characteristic of the composition and structure of the absorbing species, deconvolving a complex spectrum is nontrivial. An improved approach to spectral deconvolution is presented here that accurately represents absorption bands as discrete mathematical distributions and resolves composite absorption featu...

MgSiO3 tetragonal garnet, which is the last of the missing phases of experimentally predicted high-pressure polymorphs of pyroxene, has been discovered in a shocked meteorite. The garnet is formed from low-Ca pyroxene in the host rock through a solid-state transformation at 17 to 20 GPa and 1900° to 2000°C. On the basis of the degree of cation ordering in its crystal structure, which can be ded...

We report the first natural occurrence of the Fe-analogue of akimotoite, ilmenite-structured MgSiO3, a missing phase among the predicted high-pressure polymorphs of Fe-pyroxene, with the composition (Fe2+0.48Mg0.37Ca0.04Na0.04Mn2+0.03Al0.03Cr3+0.01)Σ=1.00Si1.00O3. The new mineral was approved by the International Mineralogical Association (IMA 2016-085) and named hemleyite in honour of Russell ...