mineral
Botryoidal Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
Hardness: 6-6.5 on Mohs scale; Color: Pale green to yellow-green; Luster: Vitreous to pearly; Crystal structure: Orthorhombic (usually in botryoidal or globular habits); Cleavage: Good in one direction; Specific Gravity: 2.80 - 2.95
- Hardness
- 6-6
- Color
- Pale green to yellow-green
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6-6.5 on Mohs scale; Color: Pale green to yellow-green; Luster: Vitreous to pearly; Crystal structure: Orthorhombic (usually in botryoidal or globular habits); Cleavage: Good in one direction; Specific Gravity: 2.80 - 2.95
Formation & geological history
Formed as a secondary or hydrothermal mineral in cavities and veins of mafic volcanic rocks (like basalt or diabase) through the alteration of calcium-rich minerals. Found in igneous and metamorphic environments.
Uses & applications
Commonly used as a gemstone (cabochons or faceted), for ornamental carvings, and as a popular mineral specimen for collectors.
Geological facts
Prehnite was the first mineral to be named after a person (Colonel Hendrik Von Prehn) in 1788. It is often called 'Grape Jade' due to its typical bubble-like, botryoidal appearance that resembles a cluster of grapes.
Field identification & locations
Identified by its distinctive pale 'celadon' green color and characteristic rounded botryoidal (globular) habit. Commonly found in South Africa (Karoo Dolerites), Australia, and the Paterson region of New Jersey, USA.
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Mineral
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