Ad
related to: rough rhyolite colorebay.com has been visited by 1M+ users in the past month
Search results
Results from the WOW.Com Content Network
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 was mined there starting 11,500 years ago. [32] Tons of rhyolite were traded across the Delmarva Peninsula, [32] because the rhyolite kept a sharp point when knapped and was used to make spear points and arrowheads. [33] Obsidian is usually of rhyolitic composition, and it has been used for tools since prehistoric times. [34]
Rhyolite – Igneous, volcanic rock, of felsic (silica-rich) composition Comendite – Hard, peralkaline igneous rock, a type of light blue grey rhyolite; Pantellerite – Peralkaline rhyolite type of volcanic rock; Scoria – Dark vesicular volcanic rock; Shonkinite – Intrusive igneous rock – a plutonic rock
The individual crystals in an aphanitic igneous rock are not distinguishable to the naked eye. Examples of aphanitic igneous rock include basalt, andesite, and rhyolite. Glassy or vitreous textures occur during some volcanic eruptions when the lava is quenched so rapidly that crystallization cannot occur. The result is a natural amorphous glass ...
The term rhyolite was introduced in 1860 by the German traveler and geologist Ferdinand von Richthofen [29] [30] [31] The naming of new rock types accelerated in the 19th century and peaked in the early 20th century. [32] Much of the early classification of igneous rocks was based on the geological age and occurrence of the rocks.
Main page; Contents; Current events; Random article; About Wikipedia; Contact us
"Imperial Porphyry" from the Red Sea Mountains of Egypt A waterworn cobble of porphyry Rhyolite porphyry from Colorado; scale bar in lower left is 1 cm (0.39 in). Porphyry (/ ˈ p ɔːr f ə r i / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate-rich, generally aphanitic matrix or groundmass.
The McNulty rhyolite, which is also known as the McNulty Gulch rhyolite, [2] [3] is described by S. F. Emmons as a fine-grained porphyritic rhyolite that is light gray in color and contains many small white feldspars and locally some small smoky quartz crystals. He mapped it as being exposed as small irregular masses in McNulty Gulch and ...
Ad
related to: rough rhyolite colorebay.com has been visited by 1M+ users in the past month