Almandine Garnet
Almandine (IMA approved), Garnet Group · Mineral Specimen / Semi-Precious Gemstone
Crystal System
Cubic (Isometric); crystals are often dodecahedral or trapezohedral. This specimen appears as an embedded, subhedral to euhedral crystal within a metamorphic matrix.
Mineral Group
Silicates; Nesosilicate (Orthosilicate) subgroup
Chemical Formula
Fe3Al2(SiO4)3
Formation Process
Metamorphic; typically forms in aluminum-rich pelitic rocks under regional metamorphic conditions (medium to high grade).
About This Crystal
Deep red to brownish-red iron-aluminum garnet. The crystal is embedded in a dark, fine-grained metamorphic host rock (likely schist or phyllite). It exhibits a vitreous to resinous luster and appears translucent to opaque where embedded.
Physical Characteristics
Color: Deep red/burgundy; Streak: White; Cleavage: None (indistinct parting); Fracture: Conchoidal to uneven; Specific Gravity: 3.9 - 4.3; Fluorescence: Inert (usually none).
Optical Properties
Refractive Index: 1.770–1.830; Singly refractive (isotropic). No pleochroism. Deep color saturation often makes it appear nearly black in thick sections.
Hardness & Durability
Origin Region
Worldwide distribution; notable sources include New York (Barton Mine), India, Madagascar, and the Alps. This specific habit is common in mica schists.
Hardness & Durability
Mohs Hardness: 6.5–7.5; Toughness: Fair to good. Exhibits high durability but can be brittle due to internal fractures.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid extreme temperature changes (thermal shock) and harsh chemicals. Ultrasonic cleaners are generally safe if the stone has no surface-reaching fractures.
Rarity & Value
Very Common as a mineral species; value for specimens depends on crystal perfection and matrix aesthetics. Gem-quality material is inexpensive to moderately priced.
Special Characteristics
May exhibit asterism (4 or 6-rayed stars) if rutile silk is present, though not visible in this specific matrix specimen.
Lore & History
Historically used in 'carbuncle' jewelry during the Victorian and Roman eras. It was traditionally viewed as a stone of protection and strength. Often associated with the Root Chakra in modern crystal lore.