Search results
Results From The WOW.Com Content Network
Magma rich in silica and poor in dissolved water is most easily cooled rapidly enough to form volcanic glass. As a result, rhyolite magmas, which are high in silica, can produce tephra composed entirely of volcanic glass and may also form glassy lava flows. [2] Ash-flow tuffs typically consist of countless microscopic shards of volcanic glass. [3]
Apache tears are rounded pebbles of obsidian or "obsidianites" composed of black or dark-colored natural volcanic glass, usually of rhyolitic composition and bearing conchoidal fracture. Also known by the lithologic term marekanite , this variety of obsidian occurs as subrounded to subangular bodies up to about 2 in (51 mm) in diameter, often ...
Helenite, also known as Mount St. Helens obsidian, emerald obsidianite, and ruby obsidianite, is a glass made from the fused volcanic rock dust from Mount St. Helens and marketed as a gemstone. [ 1 ] [ 2 ] Helenite was first created accidentally after the eruption of Mount St. Helens in 1980 .
In the eastern Mediterranean area the material was used to make tools, mirrors and decorative objects. [49] The use of obsidian tools was present in Japan near areas of volcanic activity. [50] [51] Obsidian was mined during the Jōmon period. Obsidian has also been found in Gilat, a site in the western Negev in Israel.
Tachylite (/ ˈ t æ k ə l aɪ t / TAK-ə-lyte; also spelled tachylyte) is a form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt. It is a type of mafic igneous rock that is decomposable by acids and readily fusible. [citation needed] The color is a black or dark-brown, and it has a greasy ...
For premium support please call: 800-290-4726 more ways to reach us
Obsidian with a conchoidal fracture, some weathering, and rust-red coloring. Obsidian is volcanic glass; often black and opaque. Caldera is the type locality for a resurgent dome caldera, the formation of which was first developed by C.S. Ross, R.L. Smith, and R.A. Bailey during field work at Valles in the 1960s. [19]
Pele's hair, with a hand lens as scale Strands of Pele's hair under microscope view. Pele's hair (closest modern Hawaiian translation: "lauoho o Pele " [1]) is a volcanic glass formation produced from cooled lava stretched into thin strands, usually from lava fountains, lava cascades, or vigorous lava flows.