Image: Andrew Silver (Public domain)
monoclinicuncommonSilicates (Amphibole Group)
Glaucophane
Na₂Mg₃Al₂Si₈O₂₂(OH)₂
The image displays a specimen of glaucophane, exhibiting its characteristic blue color and a somewhat fibrous to prismatic aggregate texture. A pen is included for scale, showing the specimen to be a hand-sized piece.
Glaucophane Physical Properties
Mohs Hardness
5Crystal System
monoclinicLuster
vitreousStreak Color
pale blue to grayish blueCleavage
perfect on {110}, in two directions at ~56° and ~124°Fracture
unevenSpecific Gravity
3.1Colors
blue, lavender-blue, grayish blueTransparency
translucentType Locality
California (USA), Japan, Alps (Europe)Mineral Group
Silicates (Amphibole Group)Uses
collector, scientific (indicator mineral)Associated Minerals
lawsonite, epidote, garnet, jadeite, chlorite, albite, quartzRarity
uncommonGeological Context
Glaucophane is a diagnostic mineral of blueschist facies metamorphic rocks, forming under high-pressure, low-temperature conditions typically found in subduction zones. Its presence indicates a specific tectonic environment.
