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Herkimer diamonds are double-terminated quartz crystals discovered within exposed outcrops of dolomite in and around Herkimer County, New York, and the Mohawk River Valley in the US. [1][2] They are not diamonds; the "diamond" in their name is due to both their clarity and well formed faces. Because the first discovery sites were in the village ...
Quartz. Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2. Quartz is, therefore, classified structurally as a framework silicate mineral ...
Based upon the simple, 2.9 kilometers (1.8 mi) in diameter Brent crater in Ontario, Canada, as a model, to have the types of shocked quartz exposed at the surface at the rim of the Bloody Creek structure would theoretically require removal of at least the upper half of the original final crater. That an oblique impact, as an elliptical ...
Thermoluminescence from heating chlorophane specimens on a hotplate. Triboluminescence from rubbing together two quartz crystals.. First, it will be useful to introduce some mineralogical terminology for gemstones that can glow when exposed to light, friction, or heat.
The Canadian Shield is a broad region of Precambrian rock (pictured in shades of red) that encircles Hudson Bay. It spans eastern, northeastern, and east-central Canada and the upper midwestern United States. The Canadian Shield (French: Bouclier canadien [buklje kanadjɛ̃]), also called the Laurentian Shield or the Laurentian Plateau, is a ...
Quartzite is a very hard rock composed predominantly of an interlocking mosaic of quartz crystals. The grainy, sandpaper-like surface is glassy in appearance. Minor amounts of former cementing materials, iron oxide, silica, carbonate and clay, often migrate during recrystallization, causing streaks and lenses to form within the quartzite. [1 ...
Thermoluminescence dating (TL) is the determination, by means of measuring the accumulated radiation dose, of the time elapsed since material containing crystalline minerals was either heated (lava, ceramics) or exposed to sunlight (sediments). As a crystalline material is heated during measurements, the process of thermoluminescence starts.
Cristobalite spherulites formed by devitrification from the obsidian matrix. Specimen from California, US; size: 5.9 cm × 3.8 cm × 3.8 cm (2.3 in × 1.5 in × 1.5 in). Cristobalite (/ krɪˈstoʊbəˌlaɪt /) is a mineral polymorph of silica that is formed at very high temperatures. It has the same chemical formula as quartz, SiO 2, but a ...