Forsterite
Mogok Township, Pyin-Oo-Lwin District, Mandalay Region, Myanmar
1.01 carats
© Brian Kosnar - Mineral Classics
Forsterite is a magnesium-rich olivine mineral. It forms colourless, green, yellow, yellow green, white, transparent to translucent crystals with vitreous lustre.
Forsterite Gemstones by Colour
This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
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Forsterite Gemstones by Size
This table shows distribution of Forsterite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.28 cts
Heaviest:1.22 cts
Average:0.84 cts
Total photos:3
Do you have a larger Forsterite? Why not upload a photo?
| General Information | |||||||||||||||||
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| A variety or type of: | Peridot | ||||||||||||||||
| Chemical Formula |
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| Synthetic Forsterite | |||||||||||||||||
| Synthetic forsterite: Colour - blue; Transparent; Hardness 7; RI 1.635 - 1.670; Birefringence 0.035; Biaxial/+; SG 3.26; Pleochroism: violet - blue - purple; Orthorhombic; Inclusions: gas bubbles; Fluorescence: LW - chalky white, SW - greenish-yellow. - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 16 Synthetic forsterite has a strong pleochroism and can be used as a tanzanite imitation. It is grown by crystal pulling method with Cobalt added during growth to give it a blue color. - GIA, 2018 | |||||||||||||||||
| Physical Properties of Forsterite | |||||||||||||||||
| Mohs Hardness | 6.5 to 7, Blue Chart Gem Identification (2010) | ||||||||||||||||
| Specific Gravity | 3.23 to 3.26, Blue Chart Gem Identification (2010) | ||||||||||||||||
| Tenacity | Brittle, Handbook of mineralogy (2001) | ||||||||||||||||
| Cleavage Quality | Imperfect, Handbook of mineralogy (2001) | ||||||||||||||||
| Fracture | Conchoidal, Handbook of mineralogy (2001) | ||||||||||||||||
| Optical Properties of Forsterite | |||||||||||||||||
| Refractive Index | 1.635 to 1.671, Blue Chart Gem Identification (2010) | ||||||||||||||||
| Optical Character | Biaxial/+, Blue Chart Gem Identification (2010) | ||||||||||||||||
| Birefringence | 0.034 to 0.035, Blue Chart Gem Identification (2010) Doubling | ||||||||||||||||
| Colour | |||||||||||||||||
| Colour (General) | Colorless to greenish, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||
| Colour (Chelsea Filter) | Neutral, Blue Chart Gem Identification (2010) | ||||||||||||||||
| Transparency | Transparent,Translucent, Handbook of mineralogy (2001) | ||||||||||||||||
| Lustre | Vitreous, Handbook of mineralogy (2001) | ||||||||||||||||
| Fluorescence & other light emissions | |||||||||||||||||
| Fluorescence (Short Wave UV) | Inert to weak greenish yellow, Blue Chart Gem Identification (2010) | ||||||||||||||||
| Fluorescence (Long-Wave UV) | Inert to chalky orangy, Blue Chart Gem Identification (2010) | ||||||||||||||||
| Crystallography of Forsterite | |||||||||||||||||
| Crystal System | Orthorhombic, Blue Chart Gem Identification (2010) | ||||||||||||||||
| Habit | In euhedral or subhedral crystals, typically thick, with wedge-shaped terminations, to 17 cm. Commonly granular or compact massive., Handbook of mineralogy (2001) | ||||||||||||||||
| Geological Environment | |||||||||||||||||
| Where found: | In mafic and ultramafic igneous rocks and thermally metamorphosed impure dolomitic limestones., Handbook of mineralogy (2001) | ||||||||||||||||
| Further Information | |||||||||||||||||
| Mineral information: | Forsterite information at mindat.org | ||||||||||||||||
| Significant Gem Localities | |||||||||||||||||
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