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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.
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 ...
The orange color is due to microscopic glass beads created by volcanic processes earlier in the Moon's history. Near the edges of the lunar mare are dark layers of material that cover many thousands of square kilometers. They contain many small spheres of orange and black glass that probably formed from small drops of lava that cooled very quickly.
Sideromelane from Hawaii. Sideromelane is a vitreous basaltic volcanic glass, usually occurring in palagonite tuff, [1] for which it is characteristic. It is a less common form of tachylite, with which it usually occurs together; however it lacks the iron oxide crystals dispersed in the glass, and therefore appears transparent and pure, with yellow-brown color, instead of tachylite opaque ...
Based on infrared spectroscopy, the fine-grained component of Mauna-Kea palagonite is the terrestrial material with the best match to the spectral properties of Martian dust, and is believed to be similar in composition and in origin to dusty component of the surface regolith of Mars.
When heated to their melting point, terrestrial volcanic glasses turn into a foamy glass because of their content of water and other volatiles. Unlike terrestrial volcanic glass, a tektite produces only a few bubbles at most when heated to its melting point, because of its much lower water and other volatiles content. [5]
The alkaline magmas of volcanic ocean islands will very occasionally differentiate all the way to peralkaline rhyolites, but differentiation usually ends with trachyte. [25] Small volumes of rhyolite are sometimes erupted in association with flood basalts, late in their history and where central volcanic complexes develop. [26]
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 ...