mineral
Blue Topaz
Al2SiO4(F,OH)2
AI-generated identification · may be incorrectHardness: 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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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous
Septarian Pebble
Septarian nodule / Concretion
sedimentary