Black Tiger Eye
Quartz var. Tiger's Eye (Pseudomorph after Riebeckite var. Crocidolite) · Semi-Precious Gemstone and Decorative Stone
Crystal System
Trigonal, massive to fibrous habit
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide with iron-stained crocidolite fibers)
Formation Process
Pseudomorphic replacement where quartz slowly replaces fibrous crocidolite (blue asbestos) while iron oxides stain the fibers golden-brown to dark brown and black.
About This Crystal
A polished tumbled stone showing a dark, nearly black body color with distinct chatoyant bands of golden-brown and silvery light reflections. It has a smooth, polished surface with a vitreous to silky luster when light catches the aligned microfibers.
Physical Characteristics
Body color ranges from dark brown to near black with golden or bronze chatoyant bands. White streak. Cleavage is absent due to microcrystalline fibrous structure. Fracture is uneven to splintery. Specific gravity is approximately 2.64 to 2.71. Tenacity is brittle.
Optical Properties
Doubly refractive with a refractive index of 1.544 to 1.553. Exhibits strong chatoyancy (cat's eye effect) due to the parallel fibrous structure reflecting light.
Hardness & Durability
Origin Region
South Africa, Western Australia, USA, Brazil, India
Hardness & Durability
Mohs hardness of 6.5 to 7. Good durability and toughness, suitable for daily wear in rings and pendants though care should be taken with sharp impacts.
Care & Maintenance
Clean with warm soapy water and a soft cloth. Avoid harsh chemicals, ultrasonic cleaners, and prolonged exposure to strong acids. Safe from sunlight fading under normal conditions.
Rarity & Value
Common and widely available. Value depends on the chatoyancy quality, contrast of the bands, symmetry, and polish. Typically inexpensive as a tumbled stone or polished cabochon.
Special Characteristics
Displays pronounced chatoyancy (the shimmering cat's eye band shifting across the surface as the stone moves) created by light reflecting off parallel microfibers of altered asbestos.
Lore & History
Historically used as an amulet of protection against curses and ill-wishing. In modern crystal healing, dark or black tiger eye is associated with grounding, protection, strength, and balancing the root chakra. These are traditional beliefs and not scientifically proven medical properties.