7/31/2023 0 Comments Mahogany obsidian crystal vaultsVery 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. 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 Sometimes they are even carved into Aztec or Mayan sculptures, as is the case with this Gold Sheen Obsidian jaguar to represent Tezcatlipoca.Naturally occurring volcanic glass Obsidian Like other varieties of Obsidian, they are easy to carve and take a fine polish. Gold and Silver Sheen Obsidian are mined today in Mexico, but the deposits seems to have been found discovered relatively recently. In addition to making knives and mirrors, Obsidian was also used to make talismans for protection. Each volcanic explosion creates a unique type of Obsidian, and so it is relatively easy to trace trading routes. Obsidian was widely traded throughout both South and North America. These mirrors were carved out of pure Black Obsidian and were said to reveal a person’s flaws as well as the steps needed to make the appropriate change. The name Tezcatlipoca translates to mean “smoking mirror,” likely a direct reference to Obsidian mirrors used by Mayan priests for divination and shamanic purposes. When the Aztecs practiced human sacrifice, it was an Obsidian knife that was wielded. He was depicted as a Jaguar, an incredibly potent symbol for spiritual power and authority. Tezcatlipoca was the god of night, storms, kings, shamans, war, and beauty. In Central and North America, Obsidian was a symbol of Tezcatlipoca, the chief god of the Aztec religion. Obsidian was also widely used in the Americas.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |