Blue Tourmaline
Elbaite var. Indicolite · Precious Gemstone
Crystal System
Trigonal, typically forming prismatic crystals with rounded triangular cross-sections.
Mineral Group
Silicates, specifically the Cyclosilicate subgroup (Tourmaline supergroup).
Chemical Formula
Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Formation Process
Pegmatitic and hydrothermal formation, crystallizing from cooling magma-derived fluids rich in boron, lithium, and water at moderate to high temperatures and pressures.
About This Crystal
An oval-shaped, highly polished gemstone exhibiting a vibrant teal to blue-green color. It displays high transparency, a vitreous luster, and internal clarity with minimal visible inclusions.
Physical Characteristics
Color ranges from deep blue to greenish-blue (indicolite); streak is white; no true cleavage (exhibits irregular or conchoidal fracture); specific gravity is approximately 3.01 to 3.10; brittle tenacity.
Optical Properties
Uniaxial negative with strong pleochroism (often showing lighter and darker shades of blue or green from different angles); refractive index ranges from 1.620 to 1.650; birefringence is 0.014 to 0.018.
Hardness & Durability
Origin Region
Notable sources include Brazil, Madagascar, Nigeria, Mozambique, Afghanistan, and the USA (California and Maine). Forms primarily in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs hardness of 7 to 7.5, making it durable enough for everyday jewelry wear, though its lack of cleavage makes it tough against splitting, caution is needed with sharp blows.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic or steam cleaners; store separately from harder stones like diamonds or corundum to prevent scratching.
Rarity & Value
Rare and valuable, particularly in intense, saturated blue shades (indicolite). Prices vary significantly based on color saturation, clarity, and carat weight. Treatments are uncommon for fine-quality indicolite.
Special Characteristics
Strong pleochroism and high pyroelectric and piezoelectric properties, meaning it can generate an electrical charge when heated or subjected to mechanical pressure.
Lore & History
Associated with the throat and third eye chakras, blue tourmaline is traditionally believed to enhance communication, psychic awareness, and emotional healing. Historically, all colored tourmalines were often confused with other gems like ruby or emerald until the 19th century.