What type of rock is obsidian?
Rondi: Everyone, meet Obsidian , an igneous rock that from melted rock, or magma. Obsidian is an “extrusive” rock, which means it is made from magma that erupted out of a volcano. If it was an igneous rock that formed from magma underground and did not erupt, it would have been called an “intrusive” rock.
Is metamorphic rock obsidian?
Obsidian changes to gneiss under high-grade metamorphic forces. Only under high levels of metamorphic forces will the molecules of the obsidian shape…
How are obsidian rock formed?
Obsidian is formed from quickly cooled lava, which is the parent material. 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.
Why is obsidian a igneous rock?
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.
What is obsidian rock made of?
obsidian, igneous rock occurring as a natural glass formed by the rapid cooling of viscous lava from volcanoes. Obsidian is extremely rich in silica (about 65 to 80 percent), is low in water, and has a chemical composition similar to rhyolite.
Is an obsidian a sedimentary igneous or metamorphic rock?
Obsidian. Obsidian rock are igneous rocks that form when lava cools quickly above ground. The result is a rock that cooled so fast, crystals did not get a chance to form. Obsidian is a volcanic glass with a smooth and uniform structure.
Is obsidian the hardest rock?
Obsidian is a type of igneous rock that is formed from volcanic lava. Obsidian has a hardness rating of 5-6 on Moh’s Hardness Scale.
Why is obsidian smooth?
Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic “conchoidal” fracture. This smooth, curved type of fracture surface occurs because of the near-absence of mineral crystals in the glass. The intersections of conchoidal fracture surfaces can be sharper than a razor.
Does obsidian have cleavage or fracture?
Obsidian, a naturally occuring glass, has a conchoidal fracture. Photo by Siim Seep.
Is obsidian a rock or crystal?
It is chemically similar to granite and rhyolite, which also were originally molten. Because obsidian is not comprised of mineral crystals, technically obsidian is not a true “rock.” It is really a congealed liquid with minor amounts of microscopic mineral crystals and rock impurities.
Is slate a sedimentary rock?
Slate was formed under low-grade metamorphic conditions—i.e., under relatively low temperature and pressure. The original material was a fine clay, sometimes with sand or volcanic dust, usually in the form of a sedimentary rock (e.g., a mudstone or shale).
Which type of rock is obsidian Brainly?
Volcanic glass is called obsidian. In addition to texture, igneous rocks may are classified according to their chemical composition.