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Perlite boulders with fireweed in foreground. Perlite softens when it reaches temperatures of 850–900 °C (1,560–1,650 °F). Water trapped in the structure of the material vaporises and escapes, and this causes the expansion of the material to 7–16 times its original volume.
Obsidian (/ ə b ˈ s ɪ d i. ən, ɒ b-/ əb-SID-ee-ən ob-) [5] is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth.
Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. [13] Slower cooling forms microscopic crystals in the lava and results in textures such as flow foliations, spherulitic, nodular, and lithophysal structures. Some rhyolite is highly vesicular pumice. [5]
Obsidian (Transformers), a Transformers character; Obsidian, a character in the animated TV series Trollz; Obsidian, a character in the Cartoon Network series Steven Universe; Obsidian, a synonym for dragonglass, which kills White Walkers and their soldiers in Game of Thrones; Obsidian Order, the fictional Cardassian intelligence agency from ...
Persson's most popular creation is the survival sandbox game Minecraft, which was first publicly available on 17 May 2009 [37] and fully released on 18 November 2011. Persson left his job as a game developer to work on Minecraft full-time until completion. In early 2011, Mojang AB sold the one millionth copy of the game, several months later ...
Carbonado, a form of diamond, is also cryptocrystalline. Volcanic rocks, especially of the felsic type such as felsites and rhyolites, may have a cryptocrystalline groundmass as distinguished from pure obsidian (felsic) or tachylyte (mafic), which are natural rock glasses. Agate and onyx are examples of cryptocrystalline silica .
Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.. Obsidian is a volcanic glass that was used by prehistoric people as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through knapping, or breaking off pieces in a controlled manner, such as ...
Electron spin resonance dating, or ESR dating, is a technique used to date materials, for which radiocarbon dating does not work well, such as minerals (e.g. carbonates, silicates, sulphates), inorganic biological materials (e.g., tooth enamel), inorganic archaeological materials (e.g., ceramics) and certain foods. [1]