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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 .
[3] The most common form of trinitite is green fragments of 1–3 cm thick, smooth on one side and rough on the other; this is the trinitite that cooled after landing still-molten on the desert floor. [22] [20] Around 30% of trinitite is void space, although quantities vary greatly between samples.
Bottle palm has a large swollen (sometimes bizarrely so) trunk. It is a myth that the trunk is a means by which the palm stores water. Bottle palms have only four to six leaves open at any time. The leaves of young palms have a red or orange tint, but a deep green is assumed at maturity. The flowers of the palm arise from under the crownshaft.
The Hoshikuso Pass is located northwest of Mount Kirigamine and northeast of Lake Suwa, in an area where numerous Japanese Paleolithic remains have been found. Obsidian, or hoshikuso (literally "star-shit") as it was known in the local dialect, was frequently used for stone tools and weapons in the Paleolithic and Jōmon periods as it could be easily fractured by lithic reduction to produce ...
The source of obsidian for cultures inhabiting the territory of and around Greece was the island of Milos; the Starčevo–Körös–Criș culture obtained obsidian from sources in Hungary and Slovakia, while the Cardium-Impresso cultural complex acquired obsidian from the island outcrops of the central Mediterranean.
Tephra fragments are classified by size: Ash – particles smaller than 2 mm (0.08 inches) in diameter; Lapilli or volcanic cinders – between 2 and 64 mm (0.08 and 2.5 inches) in diameter; Volcanic bombs or volcanic blocks – larger than 64 mm (2.5 inches) in diameter
Obsidian is usually of rhyolitic composition, and it has been used for tools since prehistoric times. [34] Obsidian scalpels have been investigated for use in delicate surgery. [ 35 ] Pumice, also typically of rhyolitic composition, finds important uses as an abrasive , in concrete , [ 36 ] and as a soil amendment . [ 37 ]
Ignimbrites are made of a very poorly sorted mixture of volcanic ash (or tuff when lithified) and pumice lapilli, commonly with scattered lithic fragments. The ash is composed of glass shards and crystal fragments. Ignimbrites may be loose and unconsolidated, or lithified (solidified) rock called lapilli tuff. Near the volcanic source ...