Because obsidian is metastable at the Earth's surface (over time the glass devitrifies, becoming fine-grained mineral crystals), obsidian older than Miocene in age is rare. Crystalline rocks with a similar composition include granite and rhyolite. Obsidian consists mainly of SiO 2 ( silicon dioxide), usually 70% by weight or more. Though obsidian is usually dark in color, similar to mafic rocks such as basalt, the composition of obsidian is extremely felsic. ![]() It is sometimes classified as a mineraloid. Obsidian is mineral-like, but not a true mineral because, as a glass, it is not crystalline in addition, its composition is too variable to be classified as a mineral. Tektites were once thought by many to be obsidian produced by lunar volcanic eruptions, though few scientists now adhere to this hypothesis. Intrusive formation of obsidian may occur when felsic lava cools along the edges of a dike. Extrusive formation of obsidian may occur when felsic lava cools rapidly at the edges of a felsic lava flow or volcanic dome, or when lava cools during sudden contact with water or air. Obsidian is formed from quickly cooled lava, which is the parent material. The Natural History by the Roman writer Pliny the Elder includes a few sentences about a volcanic glass called obsidian ( lapis obsidianus), discovered in Ethiopia by Obsidius, a Roman explorer. Origin and properties Obsidian talus at Obsidian Dome, California Polished snowflake obsidian, formed through the inclusion of cristobalite crystals ![]() In the past, it was used to manufacture cutting and piercing tools, and it has been used experimentally as surgical scalpel blades. Obsidian is hard, brittle, and amorphous it therefore fractures with sharp edges. Together with rapid cooling, this results in a natural glass forming from the lava. The high viscosity inhibits diffusion of atoms through the lava, which inhibits the first step ( nucleation) in the formation of mineral crystals. These flows have a high content of silica, granting them a high viscosity. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows. Obsidian is produced from felsic lava, rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. ən, ɒ b-/) is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. Usually black sometimes green or brown rarely yellow, orange, red or blue Obsidian is a fantastic Healing Stone, one of the most wanted for Meditation practice as well as Psychic readings.For other uses, see Obsidian (disambiguation). How can you get the best benefits from Obsidian Stones? Midnight Lace Sheen Obsidian, Silver Sheen Obsidian.What are the Different Types of Obsidian? It is still in used for some psychic observations today. ![]() Obsidian used as a Mirror: This stone has an extraordinary nice reflection so it has been used as mirror during Ancient Times, was also used by Nostradamus to read some observations.Obsidian is a stone used in Game of Throne: They use Obsidian as a weapon and they call it Dragonglass to defeat enemies, because of its very sharp cut.To see more information, I recommend you to consult this publication proving the test of this material. According to them, Obsidian edge can be sharper than a steel blade, can easily sharpen a steel knife. Obsidian stone is a glass like stone that was used historically for making arrowheads and knives.How obsidian Stone Age knives still cut it in surgery Obsidian was a Stone Age knives thanks to its sharp edges: when it breaks it creates very sharp edge, so it has been used for cutting from very Ancient times, but it is still used nowadays for very precise works, such has surgery.Obsidian is hard, brittle, and amorphous it therefore fractures with sharp edges. It is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth. Obsidian is a rock formed when lava spills out of the volcano, and it is formed so quickly that there is no time to crystallised. Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. Obsidian is not a mineral but it is a Black volcanic glass. Obsidian stone is certainly one of the most special healing stone.
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