![]() Very few samples of obsidian are nearly colorless. Most black obsidians contain nanoinclusions of magnetite, an iron oxide. Iron and other transition elements may give the obsidian a dark brown to black color. Pure obsidian is usually dark in appearance, though the color varies depending on the impurities present. Although newly formed obsidian has a low water content, typically less than 1% water by weight, it becomes progressively hydrated when exposed to groundwater, forming perlite. This transformation of obsidian is accelerated by the presence of water. Exceptionally old obsidians include a Cretaceous welded tuff and a partially devitrified Ordovician perlite. 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 Because individuals react differently to energies, vibrations, and/or beliefs, we cannot offer a guarantee of results or reactions.For other uses, see Obsidian (disambiguation). Please have the courtesy to contact us FIRST if there is a problem with your order.ĭisclaimer: The information provided within our store is both intuitive and derived from traditional wisdom sources which may not be verifiable by scientific methods advocated by the FDA or other governmental agencies.Request an invoice for combined shipping BEFORE checking out. ![]() To pay with a single payment, place your selections in a shopping cart-THEN check out.Please let us know if you have any special item needs. Pair up your tumbles with our lovely bowls. This is a lovely custom mix of beautiful Aqua Blue Obsidian Tumbles. The tumble will be representative of the lot picture but may vary as individuals. You are buying ONE (1) Quality Aqua Blue Obsidian Tumble unless you check the box for more than one. Obsidian draws out mental stress and tension. ![]() ![]() It blocks psychic attack and absorbs negative energies from the environment. A strongly protective stone, it forms a shield against negativity. ![]()
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