Black Tourmaline
Schorl · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Trigonal, typically forming prismatic crystals with striated faces, often tumbled into smooth stones for handling.
Mineral Group
Silicates, specifically the cyclosilicate subgroup.
Chemical Formula
NaFe2+3Al6(Si6O18)(BO33)(OH)4
Formation Process
Igneous and hydrothermal processes, primarily crystallizing in granite pegmatites and high-temperature hydrothermal veins under moderate pressure.
About This Crystal
A small, polished, tumbling-grade opaque black stone with a vitreous to sub-metallic luster on its rounded surfaces, showing a deep black body color with no visible internal structures.
Physical Characteristics
Color is deep black with a white to grey streak. It exhibits indistinct cleavage, a conchoidal to uneven fracture, specific gravity around 3.0 to 3.2, and is brittle with no notable magnetism.
Optical Properties
Singly or doubly refractive depending on orientation, typically uniaxial negative with strong pleochroism in raw specimens, though absent in opaque tumbled stones.
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, Pakistan, Afghanistan, Africa, and the USA (Maine, California). Forms in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs hardness of 7 to 7.5, making it durable for general jewelry use and resistant to scratching by most everyday objects.
Care & Maintenance
Clean with warm, soapy water and a soft brush. Avoid harsh chemical cleaners and ultrasonic cleaners. Store away from harder gems to prevent scratching.
Rarity & Value
Very common and widely available, making it affordable for collectors and jewelry makers alike. Treatments are generally unnecessary.
Special Characteristics
Exhibits pyroelectricity and piezoelectricity, generating an electrical charge when heated or subjected to mechanical pressure.
Lore & History
Historically used as an amulet for protection against negative energies and environmental pollutants. Associated primarily with the root chakra in modern crystal healing traditions.