Green Tourmaline
Elbaite · Semi-Precious Gemstone
Crystal System
Trigonal, typically forming prismatic crystals with rounded triangular cross-sections.
Mineral Group
Silicates, specifically the cyclosilicate subgroup.
Chemical Formula
Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)4
Formation Process
Forms primarily in pegmatites through late-stage magmatic crystallization and hydrothermal activity at high temperatures and pressures.
About This Crystal
The specimen is a tumbled, polished stone of vibrant emerald to forest green color. It exhibits high transparency with vitreous luster, showing internal depth and minor natural inclusions typical of tourmaline.
Physical Characteristics
Color ranges from light to dark green. Streak is white. Cleavage is indistinct, fracture is uneven to conchoidal. Specific gravity is approximately 3.00 to 3.25. Tenacity is brittle.
Optical Properties
Doubly refractive with a strong negative uniaxial sign. Exhibits strong pleochroism, showing different shades of green or yellowish-green depending on the viewing angle.
Hardness & Durability
Origin Region
Brazil, Madagascar, Afghanistan, Nigeria, and the United States (California and Maine). Found in pegmatites and hydrothermal veins.
Hardness & Durability
Mohs hardness of 7 to 7.5. Good toughness, making it generally durable for jewelry use, though internal stress fractures can make some specimens vulnerable.
Care & Maintenance
Clean with warm soapy water and a soft brush. Avoid ultrasonic cleaners and harsh chemicals. Store separately to prevent scratching softer stones and protect from prolonged direct sunlight.
Rarity & Value
Uncommon to rare depending on clarity and color saturation. Value is determined by hue, tone, saturation, and absence of inclusions. Common treatments include mild heat treatment to improve color.
Special Characteristics
Strong pyroelectric and piezoelectric properties, meaning it can generate an electrical charge when heated or compressed.
Lore & History
Historically associated with the heart chakra, green tourmaline is traditionally believed by crystal practitioners to promote compassion, healing, vitality, and prosperity, though these are cultural beliefs rather than scientific claims.