The chemical formula of mineral Olivine is indicated by (Mg,Fe)2SiO4 or Magnesium Iron Silicate. Olivine is actually a Silicate mineral. It is most commonly cut for gemstone purposes and it is most often found exhibiting nice and interesting microscope images under petrographic polarizing microscopes used in the field of optical mineralogy. Olivine is also used as refractory sands and abrasives. It is also considered as an ore if magnesium. Olivine is also usually used as mineral specimen and it is commonly found showing fascinating images under polarized microscopes for mineralogists. Olivine is also a name for a series between two end members, fayalite and forsterite. Olivine is actually known by many names. It is also known as chrysolite, evening emerald, and peridot. The term chrysolite is an old German name that was applied to gemmy olivine. However, it is now referred to light yellowish green olivine that can be more fascinating when viewed under polarizing microscopes for mineralogists. The evening emerald name is given to the gemstone variety of olivine that is usually exhibiting very interesting images when viewed under gemological microscope. But most jewelers call this gemstone variety of olivine as peridot.
Mineral Olivine is most commonly found as light near emerald green color to the more common pale yellowish green that is usually very interesting when viewed with the aid of polarized microscope used in optical mineralogy. It can be also found colorless, greenish brown to black. Olivine is usually found showing vitreous luster when viewed in reflected light of petrographic polarizing microscopes. Most crystals of mineral Olivine are found transparent to translucent in appearance. The crystal habit of mineral Olivine as described in the field of optical mineralogy including flatten tabular to box shaped crystals. However, good crystals of Olivine are rare. Olivine is also more commonly found as grains in alluvial gravels and as granular xenoliths in magnesium rich volcanic rock. Olivine is also found massive in form. Sometimes, Olivine is also found producing star shaped trillings when found as twinned.
Olivine is also commonly found showing poor cleavage in two directions at 90 degrees that can be noticed more clearly when specimen sample is evaluated using the polarizing microscopes for mineralogists, and it is more distinct in fayalite. Olivine is also found showing conchoidal fracture when specimen is viewed closely under petrographic polarizing microscopes used in optical mineralogy. The hardness measure of the mineral Olivine when specimen is evaluated using the Mohs scale method is usually 6.5 to 7. Olivine is most commonly found leaving a white streak when specimen sample is rubbed on a white porcelain streak plate. The specific gravity measure of the mineral Olivine is approximately 3.2 to 4.3 grams per cubic centimeters, which is considered above average for non-metallic minerals. The index of refraction displayed by mineral Olivine is usually 1.64 to 1.70 and it has double refraction. The best field indicators of mineral Olivine usually include color, mafic igneous or metamorphic environment of formation, hardness, density and lack of good cleavage. Olivine is usually associated with other interesting minerals including spinel, diopside, chromite, hornblende, serpentine, augite, iron-nickel meteorites and plagioclase feldspars. Olivine is usually found in ultramafic igneous rocks and marbles that formed from metamorphosed impure limestones. Mafic is a word that defines igneous rocks with high iron and magnesium content. Olivine have melting point and are the first minerals to crystallize from a mafic magma. Some ultramafic rocks can be composed of almost all olivine and these are called dunites or peridotites. Olivine can be altered to the mineral serpentine. Olivine is also found in many iro-nickel meteorites. Olivine notably occurs at several localities including Egypt, Myanmar, South Africa, Pakistan, Russia, Sweden, Norway, Brazil, France, Mexico, Australia, China, Hawaii and many more areas in USA.
