mineral

Rutilated Prehnite

Prehnite - Ca2Al(AlSi3O10)(OH)2 with Epidote/Tourmaline inclusions

Hardness: 6-6.5 on Mohs scale; Color: Pale green to yellow-green with black needle-like inclusions; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Specific Gravity: 2.80-2.95

Hardness: 6-6
Color: Pale green to yellow-green with black needle-like inclusions
Luster: Vitreous to pearly

Identified May 3, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6-6.5 on Mohs scale; Color: Pale green to yellow-green with black needle-like inclusions; Luster: Vitreous to pearly; Crystal structure: Orthorhombic; Specific Gravity: 2.80-2.95

Formation & geological history

A secondary mineral formed in cavities of mafic volcanic rocks (basalt) and occasionally in metamorphic rocks through hydrothermal alteration of plagioclase feldspars.

Uses & applications

Used primarily as a gemstone for jewelry (cabochons and beads) and as a popular specimen for mineral collectors due to its unique inclusions.

Geological facts

While often called rutilated, the black needles in green prehnite are actually usually Epidote or Schorl (Black Tourmaline) rather than Rutile. It was the first mineral named after a person (Hendrik Von Prehn).

Field identification & locations

Identify in the field by its characteristic 'seafoam' green color, botryoidal growth habits in cavities, and its association with basaltic host rocks. Commonly found in South Africa, Australia, and the USA.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

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

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral