mineral

Blue Sapphire

Corundum (Al2O3) with traces of Iron and Titanium

Hardness: 9 on the Mohs scale. Color: Deep royal blue (exhibiting pleochroism). Luster: Vitreous to Adamantine. Crystal Structure: Hexagonal (Trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 3.98 - 4.06.

Hardness: 9 on the Mohs scale
Color: Deep royal blue (exhibiting pleochroism)
Luster: Vitreous to Adamantine

Identified March 31, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed in metamorphic rocks (schist, gneiss) or igneous rocks (alkali basalt, syenite) under high pressure and temperature. Commonly found in secondary alluvial deposits (gem gravels). Geological ages vary widely from Pan-African (approx. 500-600 Ma) to Cenozoic.

Uses & applications

Primarily used as a gemstone in high-end jewelry (rings, necklaces). Industrial grade sapphires are used for scratch-resistant watch crystals, optical components, and abrasives.

Geological facts

Sapphire is the birthstone for September. The blue color is the result of intervalence charge transfer between Fe2+ and Ti4+ ions. Famous specimens include the 'Star of India' and the 'Logan Sapphire'.

Field identification & locations

Identify in the field by high density, extreme hardness (scratches almost all other minerals), and typical hexagonal barrel-shaped crystal habit. Common locations include Sri Lanka, Madagascar, Myanmar (Burma), and Montana, USA.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

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

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral