Almandine Garnet
Almandine (IMA), Garnet Group · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Cubic (Isometric); commonly found as dodecahedral or trapezohedral crystals, or in massive/granular forms.
Mineral Group
Silicates (Nesosilicates)
Chemical Formula
Fe3Al2(SiO4)3 (Iron Aluminum Silicate)
Formation Process
Metamorphic; typically forms under high pressure and temperature in pelitic metamorphic rocks like mica schists and gneisses.
About This Crystal
Deep brownish-red to dark purplish-red color, often appearing nearly black in thick or opaque specimens. Exhibits a vitreous to resinous luster. This specific specimen shows a rough, sub-translucent to opaque appearance with distinct crystalline faces visible.
Physical Characteristics
Color: Deep Red/Brown; Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 4.31; Fluorescence: Generally None.
Optical Properties
Refractive Index: 1.77-1.83 (Singly Refractive); Birefringence: None; Pleochroism: None; can rarely show 4-rayed asterism.
Hardness & Durability
Origin Region
Madagascar, India, Sri Lanka, Brazil, and the USA (notably New York and Idaho); forms in regional metamorphic environments.
Hardness & Durability
Mohs Hardness: 7.0–7.5; Good toughness and stability; very durable for daily jewelry wear.
Care & Maintenance
Clean with warm soapy water and a soft brush. Ultrasonic cleaners are usually safe, but avoid steam cleaning for fractured specimens. Store separately from diamonds.
Rarity & Value
Common; while gemstone quality is abundant, large flawless crystals are rarer. Value is determined by transparency and color saturation; often very affordable.
Special Characteristics
Characteristic deep 'iron' red color; can contain needle-like inclusions of rutile; non-magnetic though contains iron.
Lore & History
Historically used in signet rings and as a 'carbuncle' in ancient times. Symbolizes strength, protection, and endurance; associated with the Root Chakra in traditional crystal lore.