Black Tourmaline
Schorl · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Trigonal, forming prismatic crystals with striated faces, often columnar or massive
Mineral Group
Silicates, specifically the cyclosilicate subgroup
Chemical Formula
NaFe3+2Al6(Si6O18)(BO3)3(OH)4
Formation Process
Forms primarily in pegmatites and hydrothermal veins through high-temperature magmatic and metamorphic processes
About This Crystal
Opaque, jet-black specimen with a highly reflective, vitreous to submetallic luster, featuring characteristic vertical striations along the crystal prism faces
Physical Characteristics
Color is deep black, streak is white, cleavage is indistinct, fracture is uneven to conchoidal, specific gravity is approximately 3.0 to 3.2, and it is brittle with strong pyroelectric and piezoelectric properties
Optical Properties
Uniaxial negative with strong pleochroism, highly absorbent, and typically opaque in hand specimens
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, Pakistan, Madagascar, and the United States (Maine, California)
Hardness & Durability
Mohs hardness of 7 to 7.5, fair to good durability, but vulnerable to thermal shock along cleavage planes
Care & Maintenance
Clean with warm soapy water using a soft cloth, avoid ultrasonic cleaners and harsh chemicals, and store separately to prevent scratching softer stones
Rarity & Value
Common and widely available, with value determined by crystal perfection, size, and matrix association, generally ranging from inexpensive to moderately priced
Special Characteristics
Exhibits strong piezoelectric and pyroelectric properties, generating an electrical charge when heated, cooled, or subjected to mechanical pressure
Lore & History
Historically used as a protective talisman against negative energies and geopathic stress, associated primarily with the root chakra in modern crystal healing lore