Obsidian is usually 70% or more SiO2 and similar in composition to granite or rhyolite. The mineral obsidian consists of relatively pure SiO2 (the same as quartz), but of course is a non-crystalline glass. Amethyst Galleries'Mineral Gallery MINERALS Groupings Birthstones All Minerals Gemstones By...
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Obsidian is an igneous rock that forms when molten rock material cools so rapidly that atoms are unable to arrange themselves into a crystalline structure. It is an amorphous material known as a "mineraloid." The result is a volcanic glass with a smooth uniform texture that breaks with a con...
a volcanic glass similar in composition to granite, usu. dark but transparent in thin pieces, and having a good conchoidal fracture. [1790–1800; < LatinObsidiānus,printer's error forObsiānuspertaining toObsius,the discoverer (according to Pliny) of a similar mineral in Ethiopia; compare Mi...
Obsidian is a naturally occurring volcanic glassformed when lava extruded from a volcano cools rapidly with minimal crystal growth.It is an igneous rock. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite. Obsidian...
ObsidianCliff in Yellowstone National Park (Wyoming, USA) is considered a typical occurrence. The chemical compositions of red and black obsidian samples from the site are given inTable 1. The composition is rhyolitic. The cliff forms a giant flow 120–160m thick. The rock is locally columnar...
Obsidian is a volcanic glass that occurs naturally as an extrusionaryigneous rock. Obsidian is a massive glass ofvolcanoes. This word is’ huge,’ but it does mean in geology that stone (obsidian is rocky, not a mineral) is homogeneous, though this is connected to geologies. Laying, slitt...
A glassy igneous rock with a composition similar to granite. The glassy texture is a result of cooling so fast that mineral lattices were not developed.Ocean Jasper A gem material named because it is found below the high tide line of a Madagascar ocean beach. It is patterned with beautiful ...
Obsidian is mineral-like, but not a real mineral because it is not crystalline as a glass ; moreover, its composition is too variable to be classified as a mineral. It’s classified as a mineraloid sometimes. Obsidian Properties Varieties:Apache Tears, Fire Obsidian, Mahogany Obsidian, Rainbow...
The chains of polymers in the felsic lava get in the way of mineral components connecting with each other to form crystals. Also, the overall high viscosity of the lava prevents much movement from occurring. Because crystals cannot form in this situation, the lava cools into a volcanic glass ...