Black Tourmaline
Schorl · Mineral Specimen and Semi-Precious Stone
Crystal System
Trigonal system, typically forming prismatic crystals with striated faces and a triangular cross-section.
Mineral Group
Silicates, specifically the Cyclosilicate subgroup.
Chemical Formula
NaFe2+3Al6(Si6O18)(BO3)3(OH)4
Formation Process
Forms primarily in igneous and metamorphic environments, especially in granite pegmatites and hydrothermal veins.
About This Crystal
Opaque, jet-black prismatic crystal with deeply striated longitudinal faces and a sub-metallic to vitreous luster.
Physical Characteristics
Color is solid black with a white streak. It has no true cleavage, exhibiting uneven to conchoidal fracture. Specific gravity ranges from 3.0 to 3.2. It is brittle and can be pyroelectric and piezoelectric.
Optical Properties
Uniaxial negative with strong pleochroism, though often hard to observe due to the opacity of black tourmaline.
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, Pakistan, Afghanistan, the United States (California, Maine), and Africa.
Hardness & Durability
Mohs hardness of 7 to 7.5. It has fair toughness and lacks distinct cleavage planes, making it moderately durable.
Care & Maintenance
Can be cleaned with warm, soapy water and a soft brush. Avoid harsh chemicals, ultrasonic cleaners, and prolonged exposure to extreme heat.
Rarity & Value
Common and widely available. Prices are generally affordable for raw mineral specimens, depending on size and crystal perfection.
Special Characteristics
Displays strong pyroelectric and piezoelectric properties, meaning it can generate an electrical charge when heated or compressed.
Lore & History
Historically used as a protective talisman against negative energies and psychic attack. In modern crystal healing, it is associated with the root chakra and grounding.