Tanzanite
Zoisite var. Tanzanite · Precious Gemstone
Crystal System
Orthorhombic, typically forming prismatic crystals or massive habits
Mineral Group
Silicates, specifically the Sorosilicate subgroup
Chemical Formula
Ca2Al3(SiO4)(Si2O7)O(OH) with trace amounts of Vanadium
Formation Process
Metamorphic formation occurring during complex orogenic events involving intense heat, pressure, and fluid circulation within Mozambique belt rocks
About This Crystal
Featured is a striking ring containing a central emerald-cut violet-blue gemstone flanked by smaller accent stones, likely green-blue opals and small diamonds, set in precious metal. The central stone displays strong trichroism with vivid violet-blue hues, high transparency, and a vitreous luster.
Physical Characteristics
Color ranges from deep ultramarine blue to violet-blue; white streak; perfect cleavage in one direction; uneven to conchoidal fracture; specific gravity around 3.10 to 3.38; brittle tenacity; inert under UV light
Optical Properties
Biaxial positive with strong pleochroism showing deep blue, violet, and brownish-yellow/green depending on the viewing angle; high refractive index ranging from 1.691 to 1.700
Hardness & Durability
Origin Region
Merelani Hills near Mount Kilimanjaro in Northern Tanzania; formed in metamorphic environments
Hardness & Durability
Mohs hardness of 6 to 7; fair to poor toughness due to distinct cleavage; sensitive to rapid thermal shock and scratching; moderate wearability requiring protective settings for jewelry
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners, steam cleaners, sudden temperature changes, and harsh acids; store separately to prevent scratching by harder stones
Rarity & Value
Rare gemstone found exclusively in one primary location globally; value determined by deep color saturation, clarity, and cut; heat treatment is routinely applied to enhance the blue color by removing brown undertones
Special Characteristics
Notable for its intense natural trichroism and dramatic color transformation from brownish-yellow to vivid blue upon heat treatment
Lore & History
Discovered in 1967 and popularized by Tiffany & Co., tanzanite has no ancient historical lore but is modernly associated with transformation, spiritual awareness, and communication, commonly linked to the throat and third eye chakras in metaphysical practices