Term
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Definition
Ryholite
Volcanic
Felsic
Silica rich
Aphanitic
Fast Cooling |
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Term
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Definition
Granite
Coarse Grained
slow cooling
light colored |
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Term
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Definition
Diorite
Intrusive
Intermidiate |
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Term
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Definition
Gabbro
a dark, coarse-grained plutonic rock of crystalline texture, consisting mainly of pyroxene, plagioclase feldspar, and often olivine.
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Term
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Definition
Peridotite
is a dense, coarse-grained igneous rock, consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica.
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Term
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Definition
Andesite
a dark, fine-grained, brown or grayish volcanic rock that is intermediate in composition between rhyolite and basalt. |
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Term
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Definition
Porphyritic Ryolite
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Porphyritic |
| Origin |
Extrusive/Volcanic |
| Chemical Composition |
Felsic |
| Color |
Light Green |
| Mineral Composition |
Potassium Feldspar, Quartz, Sodium Plagioclase, Biotite, Hornblende |
| Miscellaneous |
Potassium Feldspar and Quartz Phenocrysts in an aphanitic (fine-grained) groundmass |
| Tectonic Environment |
Convergent Boundary - Andean-type subduction zones, intracontinental hot spots and rifts |
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Term
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Definition
Basalt
is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill.
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Term
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Definition
Obsidian
is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth.
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Term
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Definition
Pumice
is a light-colored, extremely porous igneous rock that forms during explosive volcanic eruptions. It is used as aggregate in lightweight concrete, as landscaping aggregate, and as an abrasive in a variety of industrial and consumer products.
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Term
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Definition
Scoria
is an extremely vesicular basaltic lava with very small (< 1mm) vesicles. You can find scoria all over North America: The red variety of scoria (it also comes in black) is commonly used as landscaping pebbles at Taco Bell. Landscapers know this rock as lava rock. Pumice is a froth of felsic volcanic glass.
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Term
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Definition
Volcanic Tuff
is a pyroclastic, consolidated rock composed of compacted and cemented volcanic ash, from volcanic eruptions. The rock is often soft and porous. Texture and chemical / mineralogical composition are variable, the grain size of the ash is below 4 mm (above 4 mm: volcanic breccia). |
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Term
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Definition
Volcanic Breccia
Volcanic breccias (agglomerates) comprise blocks of lava in an ash matrix and are the product of an explosive eruption.
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Term
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Definition
-
of, relating to, or denoting a group of light-colored minerals including feldspar, feldspathoids, quartz, and muscovite.
ˈfelsik/ |
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Term
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Definition
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relating to, denoting, or containing a group of dark-colored, mainly ferromagnesian minerals such as pyroxene and olivine.
Origin |
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Term
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Definition
is a term usually used to refer to igneous rock grain size. It means that the size of matrix grains in the rock is large enough to be distinguished with the unaided eye
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Term
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Definition
| relating to or denoting a rock texture, typically found in volcanic rocks, containing distinct crystals or crystalline particles embedded in a fine-grained groundmass. |
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Term
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Definition
| relating to, consisting of, or denoting fragments of rock erupted by a volcano. |
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Term
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Definition
| is a descriptive term for small crystals, and phaneritic for larger ones. Very coarse crystals (those larger than 3 centimetres, or 1.2 inches) are termed pegmatitic. igneous rock. ...is chilled so quickly that the individual minerals have little or no chance to grow. |
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Term
| What size crystals do fast cooling rocks have? |
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Definition
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Term
| What size crystals do slow cooling rocks have? |
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Definition
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