Olivine

Olivine is a group of rock-forming minerals that are typically found in mafic and ultramafic igneous rocks such as basalt, gabbro, dunite, diabase, and peridotite. They are also found in metamorphic rocks such as marble. Olivine is one of the most common minerals in the earth's subsurface, but it is hard to find at the earth's surface due to its high susceptibility to weathering.

Composition

Olivine is a silicate mineral with the general formula (Mg, Fe)2SiO4. The two end members of the olivine group are forsterite (Mg2SiO4) and fayalite (Fe2SiO4). Most olivine found in nature is closer to the forsterite end, but the two minerals form a complete solid solution series with each other.

Physical properties

Olivine is usually green in color, although its shade can vary from yellow to green to brown depending on its iron content. It has a Mohs hardness of 6.5 to 7 and a specific gravity of 3.2 to 4.5. It is transparent to translucent with a glassy luster.

Occurrence and uses

Olivine is a major component of the earth's upper mantle, and it is brought to the surface by volcanic and tectonic activity. It is also found in meteorites, including those from the moon and Mars.

Olivine has been used as a refractory material due to its high melting point and resistance to chemical attack. It is also used as a sandblasting material and in the manufacture of bricks and ceramics. In addition, olivine is sometimes cut and polished for use as a gemstone.

See also

• List of minerals
• Silicate minerals
• Igneous rock
• Metamorphic rock

References

Olivine Resources
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