Fuchsite and Glaucophane
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NameFuchsite and Glaucophane
Chemical FormulaK(Al,Cr)2(AlSi3O10)(OH)2 (Fuchsite); Na2(Mg,Fe)3Al2Si8O22(OH)2 (Glaucophane)
Mohs Hardness2-2.5 (Fuchsite), 6-6.5 (Glaucophane)
Crystal Systemmonoclinic
Streak Colorwhite to bluish white
Cleavageperfect basal (Fuchsite), perfect prismatic (Glaucophane)
Fractureuneven to subconchoidal
Specific Gravity2.77-3.22
Colorsemerald green, blue, lavender-blue
Transparencytransparent to opaque
Type LocalityGroix Island, Morbihan, Brittany, France
Mineral GroupPhyllosilicate (Mica group - Fuchsite), Inosilicate (Amphibole group - Glaucophane)
Usescollector's specimens, ornamental stone (Fuchsite), scientific interest (Glaucophane)
Rarityuncommon
Description
A specimen featuring vibrant emerald green, flaky crystals of Fuchsite intergrown with darker blue, prismatic crystals of Glaucophane, creating a striking color contrast.
Geological Context
Fuchsite is a chromium-rich variety of muscovite found in metamorphic rocks. Glaucophane is a characteristic mineral of blueschist facies metamorphic rocks, indicating high-pressure, low-temperature conditions typical of subduction zones.
