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Olivine and the Gemstone Peridot
Olivine is also the mineral of the gemstone known as “peridot.” It is a yellow-green to green gemstone that is very popular in jewelry. Peridot serves as a birthstone for the month of August. The most valued colors are dark olive green and a bright lime green. These specimens are of the mineral forsterite because the iron-rich fayalite is…
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Uses of Olivine
Olivine is a mineral that is not often used in industry. Most olivine is used in metallurgical processes as a slag conditioner. High-magnesium olivine (forsterite) is added to blast furnaces to remove impurities from steel and to form a slag. Olivine has also been used as a refractory material. It is used to make refractory…
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Olivine Rain on a Developing Star
In 2011, NASA’s Spitzer Space Telescope observed what is believed to have been tiny crystals of olivine falling like rain through the dusty cloud of gas of a developing star. This “olivine rain” was thought to have occurred as strong air currents lifted newly crystallized particles of olivine from the surface of the forming star,…
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Extraterrestrial Olivine
Olivine has been identified in a large number of stony and stony-iron meteorites. These meteorites are thought to have originated from the mantle of a rocky planet that used to occupy an orbit between Mars and Jupiter – or they might be from an asteroid that was large enough to have developed a differentiated internal structure consisting of a…
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Physical Properties of Olivine
Olivine is usually green in color but can also be yellow-green, greenish yellow, or brown. It is transparent to translucent with a glassy luster and a hardness between 6.5 and 7.0. It is the only common igneous mineral with these properties. The properties of olivine are summarized in the table. Pallasite peridot: This is one of the most incredible gemstones.…
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Olivine in Earth’s Mantle
Olivine is thought to be an important mineral in Earth’s mantle. Its presence as a mantle mineral has been inferred by a change in the behavior of seismic waves as they cross the Moho – the boundary between Earth’s crust and mantle. The presence of olivine in Earth’s interior is also confirmed by the presence of olivine…
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Composition of Olivine
Olivine is the name given to a group of silicate minerals that have a generalized chemical composition of A2SiO4. In that generalized composition, “A” is usually Mg or Fe, but in unusual situations can be Ca, Mn, or Ni. The chemical composition of most olivine falls somewhere between pure forsterite (Mg2SiO4) and pure fayalite (Fe2SiO4). In that…
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Geological Occurrence of Olivine
Most olivine found at Earth’s surface is in dark-colored igneous rocks. It usually crystallizes in the presence of plagioclase and pyroxene to form gabbro or basalt. These types of rocks are most common at divergent plate boundaries and at hot spots within the centers of tectonic plates. Olivine has a very high crystallization temperature compared to other minerals. That…
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What is Olivine?
Olivine is the name of 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 usually green in color and have compositions that typically range between Mg2SiO4 and Fe2SiO4. Many people are familiar with olivine because it is the mineral of a very popular green gemstone known as peridot.