Almandine Garnet
Garnet var. Almandine · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Cubic (Isometric); commonly occurs as dodecahedral or trapezohedral crystals
Mineral Group
Silicates (Nesosilicates); Garnet Group
Chemical Formula
Fe3Al2(SiO4)3
Formation Process
Metamorphic; typically forms under high pressure and temperature during the regional metamorphism of argillaceous sediments
About This Crystal
Deep brownish-red to blackish-red opaque to translucent crystal with a vitreous to sub-resinous luster. Surface appears slightly weathered or fractured as a rough mineral specimen.
Physical Characteristics
Color: Deep red, brown, black; Streak: White; Cleavage: None (parting may occur); Fracture: Conchoidal to uneven; Specific Gravity: 4.1-4.3; Fluorescence: Usually none; Tenacity: Brittle
Optical Properties
Refractive Index: 1.77-1.83; Singly refractive (Isotropic); typically lacks pleochroism and birefringence; dispersion is moderate
Hardness & Durability
Origin Region
Major sources include India, Sri Lanka, Brazil, Madagascar, and various metamorphic belts in the USA; commonly found in mica schists
Hardness & Durability
Mohs Hardness: 7.0-7.5; Good toughness; high stability against heat and chemicals, making it excellent for jewelry
Care & Maintenance
Clean with warm soapy water and a soft brush; safe for ultrasonic cleaners if no liquid inclusions are present; avoid sudden temperature shifts
Rarity & Value
Common; value depends on transparency and color saturation; larger transparent crystals are more valuable, while opaque rough specimens are affordable collector pieces
Special Characteristics
Can exhibit asterism (4-rayed stars) if rutile needles are present; no significant fluorescence; non-magnetic though high iron content can cause slight attraction to strong magnets
Lore & History
Historically used in signet rings and as one of the most common gemstones in late Antique and Migration Period jewelry; traditionally associated with grounding, physical strength, and the Root Chakra