Black Tourmaline
Schorl · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Trigonal system, typically forming prismatic crystals with striated faces, often occurring in massive, columnar, or tumbled forms.
Mineral Group
Silicates, specifically the Cyclosilicate subgroup.
Chemical Formula
NaFe3Al6(Si6O18)(BO33)(OH4)
Formation Process
Primarily forms in pegmatites and hydrothermal environments through the crystallization of magma rich in water and volatile elements like boron at high temperatures and pressures.
About This Crystal
The specimen is a tumbled, smooth, opaque black stone showing characteristic white quartz or mineral veinlets cutting across its surface. It has a sub-vitreous to resinous luster and an irregular, rounded pebble shape typical of tumbled pocket stones.
Physical Characteristics
Body color is solid deep black with white fracture-filling inclusions. Streak is white. Fracture is conchoidal to uneven. Specific gravity ranges from 3.0 to 3.2. Tenacity is brittle. No notable fluorescence.
Optical Properties
Singly or doubly refractive with strong birefringence (around 0.018 to 0.020). Displays strong pleochroism in raw crystalline forms, though absent in opaque tumbled black specimens like schorl.
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, Pakistan, Madagascar, Afghanistan, and the United States (Maine and California). Typically forms in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs hardness of 7 to 7.5. Good durability for daily wear, though brittle tenacity means it can fracture upon sharp impact.
Care & Maintenance
Can be cleaned safely with warm soapy water and a soft brush. Avoid harsh chemical cleaners and ultrasonic cleaners if internal fractures are present. Store separately to prevent scratching softer stones.
Rarity & Value
Common and widely accessible. Value is generally very affordable, determined by size, polish quality, and formation integrity rather than gemstone-grade clarity.
Special Characteristics
Schorl exhibits pyroelectricity and piezoelectricity, meaning it can generate an electrical charge when heated or subjected to mechanical pressure.
Lore & History
Historically used as an amulet for protection against negative energies and psychic attack. In modern crystal healing, it is heavily associated with the root chakra for grounding, energetic protection, and creating a protective shield around the body. Note these are traditional beliefs and cultural symbolisms, not scientific claims.