Almandine Garnet
Almandine (Garnet Group) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Cubic (Isometric); typically occurs as dodecahedral or trapezohedral crystals, or in rounded granular masses.
Mineral Group
Silicates (Nesosilicates); Garnet Group
Chemical Formula
Fe3Al2(SiO4)3
Formation Process
Metamorphic; typically forms during regional metamorphism of argillaceous (clay-rich) sedimentary rocks under medium to high pressure and temperature conditions.
About This Crystal
The specimen shows a deep reddish-brown, rounded 'porphyroblast' embedded in a dark, fine-grained metamorphic matrix (likely schist or phyllite). It appears translucent to opaque with a somewhat resinous to vitreous luster where fractured.
Physical Characteristics
Color: Deep red to brownish-red. Streak: White. Cleavage: None (parting may be present). Fracture: Conchoidal to uneven. Specific Gravity: 4.1-4.3. Tenacity: Brittle. Generally non-fluorescent.
Optical Properties
Refractive Index: 1.77-1.83 (Singly refractive). Birefringence: None. Dispersion: 0.027. Pleochroism: None (isotropic).
Hardness & Durability
Origin Region
Globally distributed; notable sources include New York (USA), Sri Lanka, India, Brazil, and the Alps. Often found in mica schists and gneisses.
Hardness & Durability
Mohs Hardness: 7.0 - 7.5. High toughness and excellent durability for jewelry, though sensitive to extreme thermal shock.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic and steam cleaners due to potential inclusions. Store separately to avoid scratching softer stones.
Rarity & Value
Common mineral; value is relatively low for industrial or rough specimens but increases significantly for transparent, gem-quality stones used in faceted jewelry.
Special Characteristics
May exhibit asterism (4-rayed stars) due to rutile inclusions; commonly occurs as 'phantom' growth or as porphyroblasts within host rock as seen in this image.
Lore & History
Historically known as 'Carbuncle' in ancient times. Symbolizes strength, endurance, and protection. Traditionally associated with the Root Chakra in crystal healing lore.