Willemite
Tsumeb Mine (Ongopolo Mine), Tsumeb, Oshikoto Region, Namibia
0.19 carats
© Brian Kosnar - Mineral Classics
Willemite is famous for its remarkable luminescent properties. It exhibits strong green fluorescence under short-wave ultraviolet light. Some specimens may exhibit phosphorescence, they continue to glow for some time even after the UV source is removed.
Gem quality crystals are usually small and rarely exceed two grams, but can be faceted into attractive gems.
Willemite 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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Willemite Gemstones by Size
This table shows distribution of Willemite 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:0.19 cts
Heaviest:4.89 cts
Average:1.47 cts
Total photos:16
Do you have a larger Willemite? Why not upload a photo?
| General Information | |||||||||||||||||||||
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| Chemical Formula |
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| Physical Properties of Willemite | |||||||||||||||||||||
| Mohs Hardness | 5.5, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Specific Gravity | 3.89 to 4.18, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Cleavage Quality | Distinct, Gemstones (2009) | ||||||||||||||||||||
| Fracture | Sub-Conchoidal, Gemstones (2009) | ||||||||||||||||||||
| Optical Properties of Willemite | |||||||||||||||||||||
| Refractive Index | 1.687 to 1.723, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Optical Character | Uniaxial/+, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Birefringence | 0.028 to 0.030, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Pleochroism | Nil, Gemstones (2009) | ||||||||||||||||||||
| Dispersion | Low, Gemstones (2009) | ||||||||||||||||||||
| Chatoyancy | Rare, Blue Chart Gem Identification (2010) | ||||||||||||||||||||
| Colour | |||||||||||||||||||||
| Colour (General) | Colourless, yellow, greenish-yellow, yellow-green, orange, brown, red, blue, Gemmological Tables (2004) More from other references | ||||||||||||||||||||
| Causes of Colour | Yellow, Mn2+ in tetrahedral coordination, Pragmatic Spectroscopy For Gemologists (2011) | ||||||||||||||||||||
| Transparency | Transparent,Translucent,Opaque, Gemmological Tables (2004) More from other references | ||||||||||||||||||||
| Lustre | Resinous, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Fluorescence & other light emissions | |||||||||||||||||||||
| Fluorescence (General) | Weak to strong green-(yellow), common phosphorescence, Blue Chart Gem Identification (2010) | ||||||||||||||||||||
| Fluorescence (Short Wave UV) | Shows an intense green fluorescence – some specimens may also show green phosphorescence, Gems, Sixth Edition (2006) | ||||||||||||||||||||
| Crystallography of Willemite | |||||||||||||||||||||
| Crystal System | Trigonal, Blue Chart Gem Identification (2010) More from other references | ||||||||||||||||||||
| Habit | Prismatic, massive, Gems, Sixth Edition (2006) More from other references | ||||||||||||||||||||
| Geological Environment | |||||||||||||||||||||
| Where found: | Willemite occurs in zinc deposits in limestones and is an uncommon ore of zinc., Gems, Sixth Edition (2006) More from other references | ||||||||||||||||||||
| Further Information | |||||||||||||||||||||
| Mineral information: | Willemite information at mindat.org | ||||||||||||||||||||
| Significant Gem Localities | |||||||||||||||||||||
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