Tanzanite
Zoisite var. Tanzanite · Precious Gemstone
Crystal System
Orthorhombic, typically prismatic or massive habit
Mineral Group
Silicates, specifically Sorosilicates
Chemical Formula
Ca2Al3(SiO4)(Si2O7)O(OH) with trace Vanadium
Formation Process
Metamorphic, formed during complex tectonic and metamorphic events involving high temperatures and pressures
About This Crystal
A small, translucent to transparent, fractured fragment displaying characteristic violet-blue to sapphire-blue coloration with vitreous luster
Physical Characteristics
Color ranges from violet-blue to purple, white streak, good cleavage in one direction, uneven to conchoidal fracture, specific gravity around 3.35, brittle tenacity
Optical Properties
Strong trichroism displaying blue, violet, and brownish-yellow/red depending on the viewing angle; doubly refractive with a refractive index of approximately 1.691 to 1.700
Hardness & Durability
Origin Region
Merelani Hills in the Manyara Region of Northern Tanzania; formed in metamorphic environments
Hardness & Durability
Mohs hardness of 6 to 7, fair to poor toughness due to distinct cleavage, sensitive to sudden temperature changes and thermal shock
Care & Maintenance
Clean with warm soapy water using a soft brush, avoid ultrasonic cleaners, steam cleaning, harsh chemicals, and sudden temperature fluctuations
Rarity & Value
Rare and valuable gemstone sourced exclusively from a single location in Tanzania; highly prized for intense saturation, with heat treatment commonly applied to enhance blue color
Special Characteristics
Exhibits intense trichroism and strong pleochroism, making orientation critical during cutting; widely known for its vibrant violet-blue hue
Lore & History
Discovered in 1967 and introduced by Tiffany & Co., tanzanite symbolizes transformation, truth, and higher consciousness, frequently associated with the throat and third eye chakras in crystal healing traditions