Is porphyry intrusive or extrusive?
True porphyry according to this interpretation is an intrusive rock. Extrusive (lava) rock may have a porphyritic texture but it should be named porphyritic rock, not porphyry3.
What type of rock is rhyolite porphyry?
extrusive igneous rock
Rhyolite is a fine-grained extrusive igneous rock that is mineralogically similar to granite. It chiefly contains orthoclase feldspar and quartz, but may contain lesser amounts of plagioclase feldspar, pyroxenes, biotite, and amphiboles.
Is rhyolite an intrusive?
While granite forms when magma crystallizes beneath the surface (intrusive), rhyolite forms when lava or ejected magma crystallizes (extrusive).
How is rhyolite porphyry formed?
Rhyolite usually forms in continental or continent-margin volcanic eruptions where granitic magma reaches the surface. Rhyolite is rarely produced at oceanic eruptions. Rhyolite Porphyry: Several specimens of rhyolite porphyry, each about three inches across. Click the image to enlarge.
Is pyroclastic intrusive or extrusive?
Pyroclastic rocks form from the lithification of broken fragments of rock from volcanic eruptions. This rock is made up of broken pieces of volcanic material. It is called a volcanic breccia, and is a type of extrusive igneous rock.
What color is rhyolite porphyry?
Is peridotite intrusive or extrusive?
intrusive igneous rock
peridotite, a coarse-grained, dark-coloured, heavy, intrusive igneous rock that contains at least 10 percent olivine, other iron- and magnesia-rich minerals (generally pyroxenes), and not more than 10 percent feldspar.
Which is an extrusive igneous rock?
Extrusive Igneous Rocks: Extrusive, or volcanic, igneous rock is produced when magma exits and cools above (or very near) the Earth’s surface. These are the rocks that form at erupting volcanoes and oozing fissures.
Is rhyolite resistant to weathering?
The aphanitic texture, when present, makes the primary constituents of the rhyolites even more susceptible to weathering, due to the increase in the specific surface of these minerals ( Pedron, 2007.
Is rhyolite intrusive or extrusive?
rhyolite, extrusive igneous rock that is the volcanic equivalent of granite. Most rhyolites are porphyritic, indicating that crystallization began prior to extrusion.
Is vesicular rhyolite intrusive or extrusive?
Rhyolite is an extrusive felsic (silicic) volcanic rock. The high silica content and lower temperatures of rhyolite magma result in high viscosities and violent eruptive styles.
What causes porphyry?
Porphyritic rocks are a product of igneous differentiation, and are generally formed when a column of rising magma is cooled in two stages: In the first stage, the magma is cooled slowly deep in the crust, creating the large crystal grains, with a diameter of 2mm or more.
Is rhyolite an intrusive or extrusive rock?
Granite is an intrusive rock while rhyolite is an extrusive rock.** Intrusive rocks are rocks that are formed BELOW the earth’s surface.Extrusive rocks are rocks that are formed ON the earth’s surface. What type of rock is extrusive or intrusive?
Is porphyry intrusive or extrusive rock?
True porphyry according to this interpretation is an intrusive rock. Extrusive (lava) rock may have a porphyritic texture but it should be named porphyritic rock, not porphyry 3.
Is rhyolite a porphyraceous rock?
Rocks are said to be porphyritic if their groundmass is fine-grained ar aphanitic and porphyraceous if their groundmass in visible to the naked eye. Hence, rhyolite and basalt as fine-grained volcanic rocks are porphyritic and granite, syenite, etc. as coarse-grained plutonic rocks are porphyraceous.
What is an extrusive igneous rock with a high silica content?
Rhyolite: An extrusive igneous rock. Photos and definition. An extrusive igneous rock with a very high silica content. Rhyolite: A pink specimen of rhyolite with numerous very tiny vugs with some evidence of flow structures. The specimen shown here is about two inches across.