Almandine Garnet
Almandine Garnet (Silicate Mineral) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Cubic (Isometric); typically occurs as dodecahedral or trapezohedral crystals, often found as rounded pebbles or massive aggregates in alluvial deposits.
Mineral Group
Silicates (Nesosilicates); Garnet Group
Chemical Formula
Fe3Al2(SiO4)3
Formation Process
Metamorphic formation; typically forms during regional metamorphism of clay-rich sedimentary rocks under high pressure and temperature conditions. It can also occur in igneous rocks like pegmatites.
About This Crystal
The specimen shows a deep reddish-brown to purplish-red color with a somewhat vitreous to resinous luster on fractured surfaces. It appears translucent to opaque with a rugged, weathered exterior typical of a water-worn or rough-dug garnet crystal.
Physical Characteristics
Color: Dark red to brownish-black; Streak: White; Cleavage: None; Fracture: Subconchoidal to uneven; Specific Gravity: 3.9 - 4.3; Tenacity: Brittle; Fluorescence: Generally none.
Optical Properties
Refractive Index: 1.770–1.830; Singly refractive (isotropic); lacks pleochroism due to cubic symmetry; high dispersion; may show asterism (star effect) if inclusions of rutile are present.
Hardness & Durability
Origin Region
Found globally; notable sources include India, Sri Lanka, Brazil, Madagascar, and the United States (Idaho and New York). Commonly found in metamorphic rocks like mica schists.
Hardness & Durability
Mohs Hardness: 7.0 - 7.5; Toughness: Good to Fair; stable under normal conditions but sensitive to extreme rapid temperature changes.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic and steam cleaners which may trigger fractures in included stones. Store separately from softer gems to avoid scratching them.
Rarity & Value
Common; widespread across the globe. Value is determined by transparency, color saturation, and size. Highly transparent, deep red specimens are prized for jewelry, while opaque specimens are used as abrasives.
Special Characteristics
Known for high iron content which gives it its deep color. Some specimens contain needle-like rutile inclusions that can produce a 4 or 6-ray star (asterism) when cut into cabochons.
Lore & History
Historically known as 'Carbuncle.' Associated with the Root Chakra in traditional belief systems. Ancient warriors wore garnets as amulets for protection and strength. Symbolizes fire, passion, and endurance.