Prehnite
Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
Mineral NamePrehnite
Chemical FormulaCa₂Al(AlSi₃O₁₀)(OH)₂
Mohs Hardness6
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
Cleavagegood on {001}
Fractureuneven
Specific Gravity2.85
Colorspale green, yellowish-green
Transparencytranslucent
Type LocalityLower New Street quarry, Paterson, Passaic County, New Jersey, USA
Mineral Groupphyllosilicates
Usescollector, jewelry
Associated Mineralsanhydrite, zeolites, calcite, epidote, quartz
Rarityuncommon
Description
A large, pale green, botryoidal mass of Prehnite, exhibiting a somewhat granular surface texture and a rounded, undulating form.
Geological Context
Prehnite typically forms in the vesicles and cavities of mafic volcanic rocks (like basalt and diabase) through hydrothermal alteration, often associated with zeolites and other secondary minerals.
