Garnet in Matrix
Almandine Garnet (Fe3Al2Si6O12) in Mica Schist · Mineral Specimen / Semi-Precious Gemstone
Crystal System
Cubic (Isometric); crystals are typically dodecahedral or trapezohedral. Matrix is Monoclinic.
Mineral Group
Silicates (Nesosilicates group)
Chemical Formula
Fe3Al2(SiO4)3 [often with trace amounts of Magnesium and Manganese]
Formation Process
Metamorphic; typically forms under regional metamorphism where high pressure and temperature transform clay-rich sedimentary rocks (shales) into schist.
About This Crystal
The specimen features reddish-brown, sub-to-euhedral garnet crystals embedded in a silvery-grey to buff colored micaceous matrix. The garnets appear translucent to opaque with a vitreous to resinous luster. The matrix exhibits a schistose texture with visible flaky minerals.
Physical Characteristics
Color: Dark red to brownish-red; Streak: White; Cleavage: None (parting may occur); Fracture: Conchoidal to uneven; Specific Gravity: 3.5 - 4.3; Fluorescence: Generally inert.
Optical Properties
Refractive Index: 1.770-1.830; Isotropic (Singly refractive); though garnets in matrix are primarily valued as specimens rather than for optical clarity.
Hardness & Durability
Origin Region
Commonly found in metamorphic belts; notable regions include India, Brasil, USA (New York/Idaho), and the Alps.
Hardness & Durability
Mohs Hardness: 6.5 - 7.5; Toughness: Fair to good; Stability: Stable under normal conditions, sensitive to extreme thermal shock.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic or steam cleaners as they may cause the matrix to crumble or the garnet to fracture. Store away from sunlight to prevent brittle matrix degradation.
Rarity & Value
Common; Value is determined by the size and perfection of the individual garnet crystals and the aesthetics of the matrix. Generally affordable as a collector specimen.
Special Characteristics
Garnets are known for their high refractive index and heavy weight. In matrix, they often exhibit 'porphyroblast' growth where the garnet grew larger than the surrounding mineral grains.
Lore & History
Historically, garnets were used as talismans for protection and were thought to light up the night. Many ancient cultures used them as symbols of passion and the 'energy of the earth.' In tradition, they are associated with the Root Chakra.