mineral

Prehnite with Epidote

Prehnite (Ca2Al(AlSi3O10)(OH)2) with Epidote (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH))

Hardness: 6-6.5 (Mohs); Color: Pale green to yellow-green translucent base with dark green/black needle-like inclusions; Luster: Vitreous to pearly; Crystal structure: Orthorhombic base with monoclinic inclusions; Specific gravity: 2.80-2.95.

Hardness: 6-6
Luster: Vitreous to pearly

Identified July 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed in cavities and veins of basaltic lavas or as a secondary mineral in altered igneous rocks through hydrothermal processes. Most specimens date from the Jurassic or Cretaceous periods.

Uses & applications

Primarily used as a gemstone for jewelry (cabochons and beads) and as a popular mineral specimen for collectors.

Geological facts

Prehnite was the first mineral to be named after an individual (Colonel Hendrik von Prehn) in 1788. The dark inclusions are often fibrous black or dark green Epidote needles which create a striking contrast.

Field identification & locations

Identified by its distinctive 'oil-green' or bottle-green translucency and the presence of dark, needle-like mineral inclusions. Commonly found in South Africa, Australia, and Mali.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Sandstone with Mineral Veining or Crust

Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)

sedimentary

Schist

Metamorphic

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic