RhyoliteClassification of felsic rocksRock textureName of felsic rockFine-grained (aphanitic)RhyoliteFine-grained and porphyriticPorphyritic rhyolitePyroclasticRhyolitic tuff or brecciaVesicularPumice5 more rows
Most rhyolites are light gray to pinkish in color, but red or even black rhyolites are not rare. Most rhyolites are porphyritic and are identified by the quartz phenocrysts and white to salmon K-feldspar phenocrysts.
Granite is a good approximation for the continental crust, both in density and composition. Rhyolite is a fine-crystalline felsic extrusive rock. Rhyolite is commonly pink and will often have glassy quartz phenocrysts.Feb 14, 2021
extrusiveFine grained rocks are called "extrusive" and are generally produced through volcanic eruptions.
DIORITE - phaneritic rock (large crystals) of both mafic and felsic minerals.
basalt, extrusive igneous (volcanic) rock that is low in silica content, dark in colour, and comparatively rich in iron and magnesium. Some basalts are quite glassy (tachylytes), and many are very fine-grained and compact.
Image DescriptionsIgneous RocksFelsicMaficBiotite and/or Amphibole0 to 20%0 to 30%Pyroxene0%20 to 75%Olivine0%0 to 25 %IntrusiveGraniteGabbro4 more rows
Compilations of many rock analyses show that rhyolite and granite are felsic, with an average silica content of about 72 percent; syenite, diorite, and monzonite are intermediate, with an average silica content of 59 percent; gabbro and basalt are mafic, with an average silica content of 48 percent; and peridotite is ...
​Granite: Granite is igneous(plutonic) rock.
In geology felsic refers to igneous rocks that are relatively rich in elements that form feldspar and quartz. It is contrasted with mafic rocks, which are relatively richer in magnesium and iron.
Extrusive or volcanic rocks crystallize from lava at the earth's surface. The texture of an igneous rock (fine-grained vs coarse-grained) is dependent on the rate of cooling of the melt: slow cooling allows large crystals to form, fast cooling yields small crystals.
The magma, called lava when molten rock erupts on the surface, cools and solidifies almost instantly when it is exposed to the relatively cool temperature of the atmosphere. Quick cooling means that mineral crystals don't have much time to grow, so these rocks have a very fine-grained or even glassy texture.