Search results
Results from the WOW.Com Content Network
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium -rich varieties of plagioclase ...
Olivine. The mineral olivine (/ ˈɒl.ɪˌviːn /) is a magnesium iron silicate with the chemical formula (Mg, Fe)2 Si O 4. It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, [9] it is a common mineral in Earth's subsurface, but weathers quickly on the surface. Olivine has many uses, such as the ...
Petrology. Gabbro is a coarse-grained (phaneritic) igneous rock that is relatively low in silica and rich in iron, magnesium, and calcium. Such rock is described as mafic. Gabbro is composed of pyroxene (mostly clinopyroxene) and calcium-rich plagioclase, with minor amounts of hornblende, olivine, orthopyroxene and accessory minerals. [4]
Mafic rocks have a relatively low silica content and are composed mostly of pyroxenes, olivines and calcic plagioclase. These rocks (basalt, gabbro) are usually dark coloured, and have a higher density than felsic rocks. Ultramafic rock is very low in silica, with more than 90% of mafic minerals (komatiite, dunite).
Plagioclase is the most common and abundant mineral group in the Earth's crust. Part of the feldspar family of minerals, it is abundant in igneous and metamorphic rock, and it is also common as a detrital mineral in sedimentary rock. [6][7] It is not a single mineral, but is a solid solution of two end members, albite or sodium feldspar ...
In mineralogy, silica (silicon dioxide, SiO 2) is usually considered a silicate mineral rather than an oxide mineral. Silica is found in nature as the mineral quartz , and its polymorphs . On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working ...
Solid solutions between albite and anorthite are called plagioclase, [11] or, more properly, plagioclase feldspar. Only limited solid solution occurs between K-feldspar and anorthite, and in the two other solid solutions, immiscibility occurs at temperatures common in the crust of the Earth. Albite is considered both a plagioclase and alkali ...
Monument of laterite brickstones at Angadipuram, Kerala, India, which commemorates where laterite was first described and discussed by Buchanan-Hamilton in 1807. Laterite is a soil type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of ...