Glaucophane

Na₂Mg₃Al₂Si₈O₂₂(OH)₂

The image displays a dark blue, prismatic to fibrous aggregate of glaucophane crystals, showing its characteristic color and form, with a pen for scale.

Glaucophane Physical Properties

Mohs Hardness

Crystal System

monoclinic

Luster

vitreous

Streak Color

pale blue to bluish-white

Cleavage

perfect on {110} (two directions at ~56° and ~124°)

Fracture

uneven to subconchoidal

Specific Gravity

3.08

Colors

blue, lavender-blue, grayish-blue

Transparency

translucent to opaque

Type Locality

California (USA), Japan, Alps (Europe)

Mineral Group

Silicates (Amphibole Group)

Uses

collector, scientific (indicator mineral)

Associated Minerals

lawsonite, jadeite, epidote, garnet, chlorite, albite

Rarity

uncommon

Geological Context

Glaucophane is a key indicator mineral for blueschist facies metamorphism, forming under high-pressure, low-temperature conditions typically found in subduction zones. Its presence signifies a unique tectonic environment.

Back to Collection

Related Specimens

Boulangerite

Crocoite

Boracite

Cristobalite

Stibnite

Feldspar