NMR Spectral Characteristics of Ultrahigh Pressure High Temperature Impact Glasses of the Giant Kara Crater (Pay-Khoy, Russia)

In this study, we carried out the analysis of the impact melt vein glasses from the Kara impact crater (Russia) in comparison to low-pressure impact melt glasses (tektites) of the Zhamanshin crater (Kazakhstan). 27Al, 23Na, and 29Si MAS NMR spectra of the samples of these glasses were analyzed. The samples of the natural glass contained inclusions of crystalline phases, paramagnetic elements that greatly complicate and distort the NMR signals from the glass phase itself. Taking into account the Mossbauer distribution of Fe in these glasses, the analysis of the spectra of MAS NMR of glass network-former (Si, Al) and potential network-modifiers (Na) of nuclei leads to the conclusion that the Kara impact melt vein glasses are characterized by complete polymerization of (Si,Al)O4 tetrahedral structural units. The NMR features of the glasses are consistent with the vein hypothesis of their formation under conditions of high pressures and temperatures resulting in their fluidity, relatively slow solidification with partial melt differentiation, polymerization, and precipitation of mineral phases as the impact melt cools. The 70 Ma stability of the Kara impact vein glass can be explained by the stabilization of the glass network with primary fine-dispersed pyroxene and coesite precipitates and by the high polymerization level of the impact glass.

Distinguishing volcanic from impact glasses—The case of the Cali glass (Colombia)

Natural glass occurs on Earth in different geological contexts, mainly as volcanic glass, fulgurites, and impact glass. All these different types of glasses are predominantly composed of silica with variable amounts of impurities, especially the alkalis, and differ in their water content due to their mode of formation. Distinguishing between different types of glasses, on Earth and also on the Moon and on other planetary bodies, can be challenging. This is particularly true for glasses of impact and volcanic origin. Because glass is often used for the determination of the age of geological events, even if out of geological context, as well as to derive pressure and temperature constraints, or to evaluate the volatile contents of magmas and their source regions, we rely on methods that can unambiguously distinguish between the different types of glasses. We used the case of the Cali glass, found in an extended area close to the city of Cali in western Colombia, which was previously suggested to be of impact or volcanic origin, to show that, using a multimethod approach (i.e., combining macroscopic observations, chemical and isotopic data, and H2O content), it is possible to distinguish between different formation modes. A suite of Cali glass samples was analyzed using electron microprobe, instrumental neutron activation analysis, thermal ionization mass spectrometry, and Fourier-transform infrared spectroscopy, allowing us to definitively exclude an impact origin and instead classify these glasses as a rhyolitic volcanic glass (obsidian). Our results suggest that other “unusual glass occurrences” that are claimed, but not convincingly proven, to be of impact origin should be reexamined using the same methodology as that applied here.

The occurrence of iron silicides in a fulgurite: Implications for fulgurite genesis

ABSTRACT Rapidly formed eutectic textures are observed in Fe silicides in a fulgurite from Michigan. The 14 cm-diameter fulgurite was formed in sandy glacial till in 2014 near Houghton Lake, Michigan. Spherical droplets of iron silicides up to ∼200 μm in diameter were found in the natural glass. Back-scattered electron images of some droplets show a eutectic intergrowth texture of two iron silicides with individual crystals up to ∼1 μm in maximum dimension. X-ray diffraction study showed the specimens to be an intergrowth of naquite (FeSi) and linzhiite (FeSi2) or naquite and xifengite (Fe5Si3). Droplets also contain minor native silicon, Fe-Ti silicides, and/or other Ti- rich phases which were discovered during TEM observations. It is important to note that the lower-temperature phase luobusaite (Fe3Si7) was not observed in any droplets, indicating rapid quenching of the fulgurite, consistent with a natural origin during a lightning strike as opposed to an artificial origin, e.g., resulting from a downed power line.

Experimental Research on Hybrid Natural/Glass Fiber Based Epoxy Composite

Polymeric substances fortified with engineered strands like glass, carbon, and aramid give addition of over the top firmness and vitality to weight proportion when contrasted with ordinary substances like wooden, concrete and numerous others. In spite of those favors present day examines are occurring inside the territory of home grown composites because of low primer cost and accessibility of simplicity. Hand arrangement approach is utilized for setting up the examples, with different weight division of bi-directional glass fiber. The proportion of filler is fixed with/without 10 wt.- %. Examples were cut from the created overlay with regards to the ASTM norms for various tests. The precise experimentation prompts self discipline of good estimated way parameters and texture factors that dominatingly impact the harm charge. It has been found that put on rate lower with developing fiber weight rate. Mechanical homes of composites are increments with development of fiber stacking. The mechanical and wear conduct of stuffed composites is more noteworthy propelled then unfilled composites.

Research gemology and mineralogy characteristics of Tektite in North region of Da Lat City

Tektite in northern of Da Lat city is a kind of natural glass, formed from meteorite collisions with Earth, have basic elements Si, Al, Fe, Mg. Typical shapes inclued debris, drops, oval, dumbbell, flat sphere, flat mace, short prism with external shape characterized by holes covering the surface. Typical color is black, sometimes brownish green at thin edges. The average density is about 1.45 g/cm3, a refractive index of about 1.50, with prolonged gas and the inclusion of carbonate, lechatelierite characteristic of natural glass. Tektite in Northern Dalat is proven to have a planetary origin that fits the hypothesis that they are formed by meteorite impacts. Tektite in the area can be used in jewelry.