Newly obtained near-infrared reflectance spectra for features on or near the Aristarchus Plateau demonstrate he diversity of compositions in the region. t!ighland units are of three probable compositions: a feldspar and elinopyroxene assemblage; a probable clinopyroxene, olivine, and possibly feldspar assemblage; and an assemblage composed of olivine or olivine and feldspar. The feldspar-elinop...

Mineral dusts originating from Earth's crust are known to be important atmospheric ice nuclei. In agreement with earlier studies, feldspar was found as the most active of the tested natural mineral dusts. Here we investigated in closer detail the reasons for its activity and the difference in the activity of the different feldspars. Conclusions are drawn from scanning electron microscopy, X-ray...

Cation exchange experiments between gem quality sanidine [Formula: see text] and KCl melt produced chemical alteration of alkali feldspar starting at the grain surface and propagating inwards by highly anisotropic Na-K interdiffusion on the alkali sublattice. Diffusion fronts developing in b-direction are very sharp, while diffusion fronts within the a-c-plane are comparatively broad. Due to th...

Fibrous tremolite is a mineral species belonging to the amphibole group. It is present almost everywhere in the world as a natural contaminant of other minerals, like talc and vermiculite. It can be also found as a natural contaminant of the chrysotile form of asbestos. Tremolite asbestos exposures result in respiratory health consequences similar to the other forms of asbestos exposure, includ...

Feldspar minerals are the most common rock formers in Earth's crust. As such they play an important role in subjects ranging from geology to climate science. An atomistic understanding of the feldspar structure and its interaction with water is therefore desirable, not least because feldspar has been shown to dominate ice nucleation by mineral dusts in Earth's atmosphere. The complexity of the ...

Abstract The eruption of the Tambora volcano in 1815 was initiated by two precursory Plinian falls and formed generations pyroclastic density current (PDC) deposits. In this study, we found slight changes phenocrysts (modal mineralogy, content, size), bulk-rock feldspar microlite chemical compositions, bubble number densities through stratigraphic position. fall units are characterized a lower ...

Abstract Kaolin is widespread as a result of the alteration in San José Sn-Ag deposit located Oruro, Bolivia. This study presents chemical, mineralogical and thermal characterization kaolinitic deposit, which necessary to determine their optimal applications. Mineral phases these white silty materials were determined by X-ray diffraction (XRD) are quartz, kaolinite, K-feldspar, muscovite, illit...

40 Ar/ 39 Ar analyses were made on maruyamaite (potassium-dominant tourmaline) from tourmaline-quartz-feldspar rocks discovered within the Kumdy-Kol microdiamond deposit (Kokchetav massif, North Kazakhstan). Turmaline yielded well-defined plateau age spectra whose values coincide error - ages of 502.3±8.0, 502.2±8.0, 506.0±8.0 Ma. These are much younger than 530±2 Ma determined for high-pressur...