mineral
Blue Topaz
Al2SiO4(F,OH)2
Hardness: 8 on Mohs scale. Color: Electric blue. Luster: Vitreous. Crystal Structure: Orthorhombic. Cleavage: Perfect basal. Specific Gravity: 3.49-3.57.
- Hardness
- 8 on Mohs scale
- Color
- Electric blue
- Luster
- Vitreous
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Physical properties
Hardness: 8 on Mohs scale. Color: Electric blue. Luster: Vitreous. Crystal Structure: Orthorhombic. Cleavage: Perfect basal. Specific Gravity: 3.49-3.57.
Formation & geological history
Formed as a silicate mineral in igneous rocks like pegmatite and rhyolite, and in hydrothermal veins. The blue color in many commercial stones is usually achieved by irradiating and heating natural colorless topaz.
Uses & applications
Primarily used in jewelry (rings, pendants, earrings) due to its hardness and clarity. It is also a birthstone for November/December.
Geological facts
Natural blue topaz is quite rare in nature; most commercial 'Swiss' or 'London' blue topaz is colorless material that has been treated. It is the state gemstone of Texas and Utah.
Field identification & locations
Identify by its high hardness (scratches glass/quartz) and perfect basal cleavage. It is commonly found in Brazil, Nigeria, and Sri Lanka. Collectors look for clarity and intensity of hue.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock
![Green Apatite on Albite (Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]) — mineral](https://media.rockidentification.com/2391a63f-fb20-47d5-af9a-2035851eb32e-thumbnail.jpg)
Green Apatite on Albite
Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]
mineral