Green Prehnite
Prehnite · Semi-Precious Gemstone and Mineral Specimen
Crystal System
Orthorhombic, typically found in botryoidal, globular, or reniform aggregates, also tabular crystals.
Mineral Group
Silicates (Phyllosilicate)
Chemical Formula
Ca2Al2Si3O10(OH)2
Formation Process
Hydrothermal and low-grade metamorphic processes, typically occurring in cavities of basaltic and volcanic rocks.
About This Crystal
A pale apple-green to yellow-green translucent tumbled or roughly shaped mineral specimen with a vitreous to pearly luster and smooth, rounded contours.
Physical Characteristics
Color is pale green; streak is white; cleavage is distinct on one plane (rarely observed in tumbled stones); fracture is uneven; specific gravity is approximately 2.80-2.95; tenacity is brittle.
Optical Properties
Biaxial (+), refractive index ranges from 1.611 to 1.673, birefringence is 0.020 to 0.033, occasionally exhibits chatoyancy when fibrous.
Hardness & Durability
Origin Region
South Africa, Mali, Australia, USA (New Jersey), and Scotland.
Hardness & Durability
Mohs hardness of 6 to 6.5; moderate durability suitable for pendants and earrings, but requires care in rings due to distinct cleavage.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners, harsh chemicals, and prolonged exposure to direct sunlight or extreme heat.
Rarity & Value
Uncommon; value depends on color saturation, transparency, and size, with vibrant green or chatoyant specimens commanding higher prices.
Special Characteristics
Can occasionally display chatoyancy (cat's eye effect) or occur in appealing botryoidal habits with epidote inclusions.
Lore & History
Discovered in South Africa by Colonel Hendrik von Prehn in the late 18th century. In crystal healing, it is known as the stone of unconditional love and is associated with the heart chakra, believed to connect the heart and the will.