mineral

Blue Sapphire (Raw)

Corundum (Al2O3)

Hardness: 9 on Mohs scale; Color: Deep blue; Luster: Vitreous to sub-adamantine; Crystal system: Trigonal/Hexagonal; Cleavage: None (parting); Specific Gravity: 3.95-4.03.

Hardness: 9 on Mohs scale
Color: Deep blue
Luster: Vitreous to sub-adamantine

Identified July 5, 2026More mineral →

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Physical properties

Hardness: 9 on Mohs scale; Color: Deep blue; Luster: Vitreous to sub-adamantine; Crystal system: Trigonal/Hexagonal; Cleavage: None (parting); Specific Gravity: 3.95-4.03.

Formation & geological history

Formed in aluminum-rich metamorphic rocks (like marble or schist) and igneous rocks (syenites) through high pressure and temperature. Large crystals are often found in alluvial deposits (placer deposits) after eroding from their host rock.

Uses & applications

Used primarily in fine jewelry (faceted gemstones), industrial abrasives due to extreme hardness, and specialized scientific windows or watch crystals.

Geological facts

Sapphire is the same mineral as Ruby; the only difference is the trace elements (iron and titanium create blue, while chromium creates red). It is the second hardest natural substance on Earth after diamond.

Field identification & locations

Field identification focuses on its extreme hardness (cannot be scratched by quartz or steel) and its high density. Found commonly in Sri Lanka, Madagascar, Myanmar, and Montana, USA.