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Before Obsidian Butte was emplaced and thus became available for obsidian production, people in the region used obsidian from the Coso volcanic field; [44] this trend away from Coso towards Obsidian Butte was recognized even before the exact timing of the Obsidian Butte eruption was known. [42] How the magmas are formed is controversial.
Obsidian talus at Obsidian Dome, California Polished snowflake obsidian, formed through the inclusion of cristobalite crystals. 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.
Geologic map of the Sonoma Volcanics. The Sonoma Volcanics are a geologic formation of volcanic origin that is widespread in Napa and Sonoma counties, California.Most of the formation is Pliocene in age and includes obsidian, perlitic glass, diatomaceous mud, pyroclastic tuff, pumice, rhyolite tuffs, andesite breccias and interbedded volcanic lava flows.
The volcano underwent its most recent eruptions 1,300 years ago, producing the Big Obsidian flow. A silicic deposit, it is made up of rhyolite and features a number of lava blocks . Although it is frequently cited as the largest Holocene obsidian formation in the United States, its area of 1.09 square miles (2.8 km 2 ) and volume of 0.031 cubic ...
Because the Glass Buttes complex has abundant, high-quality obsidian, the Bureau of Land Management has reserved 36 square miles (93 km 2) as a free-use area where the public can gather obsidian for private use. No permits are required; however, individuals can only remove 250 pounds (110 kg) of obsidian per year.
Obsidian from the Coso Volcanic Fields was heavily exploited by Native American Coso People to make knives, projectile points, and the like (Hughes 1998). The chief period of exploitation was between approximately 3000 and 1000 years ago, when people mined obsidian by constructing benches in hillsides and digging deep pits to access raw materials (Elston and Zeier 1984; Gilreath and Hildebrand ...
Edziza obsidian found in coastal areas of southeast Alaska. Edziza obsidian is a naturally formed volcanic glass found at the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It occurs in at least four geological formations of the volcanic complex and was widely used by indigenous peoples during the pre-Columbian era.
The Mono Lake Volcanic Field forms the northernmost part of the chain and consists of two volcanic islands in the lake and one cinder cone volcano on its northwest shore. Most of the Mono Craters , which make up the bulk of the northern part of the Mono–Inyo chain, are phreatic (steam explosion) volcanoes that have since been either plugged ...