Kimberlite: A Rare, Brecciated Diamond Bearing Mantle Rock
Kimberlite is a potassic to ultrapotassic ultramafic rock with inequigranular texture. It is a rare type of peridotite with many xenoliths and xenocrysts, including, on
Rocks
Peridotites: Dense, Coarse-Grained Ultramafic Intrusive Igneous Rocks
Peridotites are dense, coarse-grained, dark-colored ultramafic plutonic rocks with at least 40% olivine by volume. Members are dunite, kimberlite, harzburgite, wehrlite and lherzolite. Others are
A Detailed Guide into Nepheline Syenite Rocks
Nepheline syenite is a coarse-grained, pale-colored (white, gray, or pinkish) intrusive igneous rock that resembles granite. Its chemical composition is intermediate to felsic and has
Syenite: A Coarse-grained Granite-Like Plutonic Rock
Syenite is a coarse-grained, mostly light-colored intrusive rock with an intermediate to felsic composition. It has mainly alkali feldspar, lesser plagioclase, and one or more
Everything You Ought to Know about Andesite Rock
Andesite is a fine-grained, intermediate volcanic or extrusive igneous rock. Its composition lies between basalt and dacite, and it has mainly sodium-rich plagioclase and one
Diorite: A Salt-and-Paper Looking Coarse-Grained Rock
Diorite is a coarse-grained, intermediate plutonic, or intrusive igneous rock. It has mainly plagioclase feldspar, biotite, hornblende, sometimes pyroxenes, and other minerals. This rock’s composition
Dunite: A Coarse-grained, Olivine-rich Greenish Plutonic Rock
Dunite is a coarse-grained, pale green to olive-green, ultramafic intrusive igneous rock with more than 90% olivine. It also may have smaller amounts of pyroxene,
What Is Arkose Sandstone? How Does it Form and Where?
Arkose is a detrital sedimentary sandstone with over 25% feldspar. It comprises mainly quartz and feldspar clasts with minor amounts of mica and some heavy
Obsidian: A Hard, Brittle Natural Volcanic Glass or Rock
Obsidian is a felsic, naturally occurring volcanic glass. It has 69-77% silica and is relatively high in alkalis (>7%) and low in iron and magnesium