mineral

Sapphirine in Matrix

Sapphirine (Mg,Al)8(Al,Si)6O20

Hardness: 7.5; Color: light to dark blue, green, or gray; Luster: Vitreous; Crystal structure: Monoclinic; Cleavage: Poor/indistinct; Specific Gravity: 3.4 - 3.58

Hardness: 7
Color: light to dark blue, green, or gray
Luster: Vitreous

Identified March 3, 2026More mineral →

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Physical properties

Hardness: 7.5; Color: light to dark blue, green, or gray; Luster: Vitreous; Crystal structure: Monoclinic; Cleavage: Poor/indistinct; Specific Gravity: 3.4 - 3.58

Formation & geological history

Formed under high-grade metamorphic conditions (granite facies metamorphism) in silica-poor, aluminum-and-magnesium-rich environments; typically Proterozoic to Archean in age.

Uses & applications

Primarily of interest to mineral collectors and as a research specimen for geologists studying deep-crustal metamorphic processes; occasionally used as a gemstone if transparent.

Geological facts

Sapphirine is named for its sapphire-like color, although it is chemically distinct from sapphire (corundum). It is an indicator mineral for extreme metamorphic temperatures exceeding 800 degrees Celsius.

Field identification & locations

Found in high-grade metamorphic terrains like those in Greenland, Madagascar, and Sri Lanka. Identify in the field by its high hardness, blue-green hue, and association with minerals like spinel, phlogopite, and orthopyroxene.