gemstone
Sapphire
Corundum (Al2O3)
Hardness: 9.0 on Mohs scale; Color: Deep blue; Luster: Vitreous to sub-adamantine; Crystal Structure: Trigonal/Hexagonal; Specific Gravity: 3.98-4.06
- Hardness
- 9
- Color
- Deep blue
- Luster
- Vitreous to sub-adamantine
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Physical properties
Hardness: 9.0 on Mohs scale; Color: Deep blue; Luster: Vitreous to sub-adamantine; Crystal Structure: Trigonal/Hexagonal; Specific Gravity: 3.98-4.06
Formation & geological history
Formed in aluminum-rich metamorphic rocks (schist, gneiss) or igneous rocks (syenite, pegmatite) under high pressure and temperature. Commonly found in secondary alluvial deposits.
Uses & applications
Predominantly used as high-end jewelry (rings, bracelets), but also in industrial applications as abrasive or for scratch-resistant watch crystals and windows.
Geological facts
Sapphire is the birthstone for September. While blue is the most famous color, sapphires can occur in every color except red (which is classified as ruby).
Field identification & locations
Identify by its extreme hardness (scratches glass/steel easily) and deep saturation. Naturally found in Sri Lanka, Madagascar, Myanmar, and Montana, USA.
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ZrO2 (Cubic Zirconia) or C (Diamond)
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Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)
mineral
Cubic Zirconia (or possibly Diamond)
Zirconium dioxide (or Carbon)
gemstone
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
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Faceted Gemstone
Unknown transparent mineral, possibly Diamond (C), Cubic Zirconia (ZrO2), Quartz (SiO2), or Glass
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