What is forsterite used for?
Uses: As gemstones, industrial uses as refractory sands and abrasives, an ore of magnesium and as mineral specimens. Forsterite is named for the German naturalist, Johann Forster.
How do you identify forsterite?
Forsterite is a colorless to greenish transparent member of the olivine mineral family, which also includes peridot. Forsterite has a heavy magnesium chemical composition and large crystals are not common, but they are highly sought after by collectors.
How common is forsterite?
Occurrence. Pure forsterite is rare, but is found in certain metamorphosed siliceous dolomitic limestones (marbles). Olivine with compositions between Fo96 and Fo82 are major constituents in ultramafic rocks such as dunite and peridotite, and in prograde metamorphosed serpentintes.
Where does forsterite occur?
Forsterite occurs in two parageneses in the Mogok Stone Tract. One is as an accessory mineral in Mg-rich metamorphic marbles associated with other Mg-rich silicates such as spinel, phlogopite and humite group minerals.
What is the relief of forsterite?
Petrographic Data File
| Forsterite | |
|---|---|
| Property | Value |
| Distinguishing Features | Colorless to olive green in thin section. Second-order interference colors. High relief. Lack of cleavage. H= 6.5-7. G = 3.2. Streak is colorless or white. May be confused with epidote, which has cleavage and a is pistachio-green in hand sample. |
What mineral group does forsterite belong to?
Olivine Group
Olivine Group. Fayalite-Forsterite Series, and the Forsterite-Tephroite Series. The magnesium analogue of Fayalite, Tephroite, and Calcio-Olivine. Visit gemdat.org for gemological information about Forsterite.
Is Peridot a forsterite?
As peridot is a magnesium-rich variety of olivine (forsterite), the formula approaches Mg2SiO4. Its green color is dependent on the iron contents within the structure of the gem. Peridot occurs in silica-deficient rocks such as volcanic basalt and pallasitic meteorites.
Is forsterite a silicate?
forsterite-fayalite series, the most important minerals in the olivine family and possibly the most important constituents of the Earth’s mantle. Included in the series are the following varieties: forsterite magnesium silicate (Mg2SiO4) and fayalite iron silicate (Fe2SiO4).
Is forsterite the same as peridot?
Forsterite is the magnesium rich member with a pure formula of Mg2SiO4. Olivine’s formula is written as (Mg, Fe)2SiO4 to show the substitution of the magnesium and iron. Peridot is usually closer to forsterite than fayalite in composition although iron is the coloring agent for peridot.