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Llanite is a porphyritic rhyolite with distinctive phenocrysts of blue quartz (a rare quartz color) and perthitic feldspar (light grayish-orangeish). The brown, fine-grained groundmass consists of very small quartz, feldspar, and biotite mica crystals.
Rhyolite magmas can be produced by igneous differentiation of a more mafic (silica-poor) magma, through fractional crystallization or by assimilation of melted crustal rock . Associations of andesites , dacites , and rhyolites in similar tectonic settings and with similar chemistry suggests that the rhyolite members were formed by ...
The ancient Ballena River brought rhyolite-gravel, or "Poway" clasts, from a region in present-day Sonora, Mexico to the Pacific Ocean. Its sediments deposited into an alluvial fan–submarine canyon–submarine fan complex extending for miles offshore. Remnants of submarine fan facies outcrops are found as far west as the northern Channel Islands.
Sillar is a variety of rhyolite, which is a type of volcanic rock. Although sillar is of rhyolitic composition, it has been erupted from volcanoes which mostly erupt andesite lava, and sillar contains small fragments of andesite. A pink variety of sillar owes its colour to crystals of hematite within the rock. A white variety lacks these ...
[2] [3] Evidence for the Indian Rock rhyolite being from slip-strike activity comes from the site being in the path of the Mendocino Triple Junction as it migrated northward. Similar sites can be found nearby, including only one block east of Indian Rock Avenue, where the 0.39-acre (1,600 m 2) Mortar Rock Park is found.
Rhyolite Ridge is the only known lithium-boron deposit in North America and one of only two known such deposits in the world. There is currently only one lithium producing mine in the U.S ...
The rhyolite tuff member is the lowest stratigraphic exposure of the Newbury Volcanic Complex. This member is made up of glassy fragments of rhyolitic tuff that is heavily sheared and is crudely held together and is about 6 m in thickness and yellowish-brown to brownish-gray in color.
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