Volcanic glass
Volcanic glass is the
Origin
Volcanic glass is formed when
The mechanisms controlling formation of volcanic glass are further illustrated by the two forms of basaltic glass,
Of the cooling mechanisms responsible for forming volcanic glass, the most effective is quenching by water, followed by cooling by entrained air in an eruption column. The least effective mechanism is cooling at the bottom of a flow in contact with the ground.[4]
Types
Most commonly, volcanic glass refers to
Other types of volcanic glass include the following:
- Pumice, which is considered a glass because it has no crystal structure.
- Apache tears, a kind of nodular obsidian.
- Tachylite (also spelled tachylyte), a basaltic glass with relatively low silica content.
- Sideromelane, a less common form of tachylyte.
- Palagonite, an alteration product of basaltic glass.[8]
- Hyaloclastite, a hydrated tuff-like breccia of sideromelane and palagonite.
- Pele's hair, threads or fibers of volcanic glass, usually basaltic.
- Pele's tears, tear-like drops of volcanic glass, usually basaltic.
- Limu o Pele (Pele's seaweed), thin sheets and flakes of brownish-green to near-clear volcanic glass, usually basaltic.
Alteration
Volcanic glass is chemically unstable and readily decomposes. Water molecules readily react with the open, disordered structure of volcanic glass, removing soluble cations from the glass and precipitating secondary (
References
- ISBN 9780385181013. Retrieved 7 April 2022.
- ^ ISBN 3540127569.
- ^ Fisher & Schmincke 1984, p. 96-97.
- ^ ISBN 978-3-540-43650-8.
- ^ Fisher & Schmincke 1984, pp. 75–76.
- .
- .
- ^ Fisher & Schmincke 1984, p. 314-327.
- ^ Fisher & Schmincke 1984, p. 312.