Prehnite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY 4.0)
Mineral NamePrehnite
Chemical FormulaCa₂Al(AlSi₃O₁₀)(OH)₂
Mohs Hardness6.5
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
Cleavagegood on {001}
Fractureuneven
Specific Gravity2.87
Colorspale green, yellow-green, white, gray, colorless, light blue-green
Transparencytranslucent
Type LocalityMaharashtra, India
Mineral GroupSilicates
Usesjewelry, collector, ornamental stone
Associated Mineralszeolites, apophyllite, calcite, copper
Rarityuncommon
Description
This image displays a rectangular, step-cut prehnite gemstone, weighing 6.17 carats, exhibiting a pale greenish-blue hue and translucent clarity with some visible internal inclusions.
Geological Context
Prehnite typically forms as a secondary mineral in the vesicles and cavities of basaltic volcanic rocks, often associated with low-grade metamorphic or hydrothermal alteration processes.
