Sillimanite-bearing Quartzite
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NameSillimanite-bearing Quartzite
Chemical FormulaSiO2 (Quartz), Al2SiO5 (Sillimanite)
Mohs Hardness7
Streak ColorWhite
CleavageNone to poor (due to quartz dominance and tough nature)
FractureConchoidal to uneven
Specific Gravity2.8
Colorswhite, reddish-brown, dark grey
TransparencyTranslucent to opaque
Type LocalityManzat, Puy-de-Dôme Department, France
Mineral GroupSilicates
UsesNeolithic tools (axes), collector's item
Associated Mineralsquartz, sillimanite
Rarityuncommon
Description
A polished, elongated rock with mottled patterns of white, reddish-brown, and dark grey, featuring distinct reddish veins throughout its surface.
Geological Context
This rock is a high-grade metamorphic rock, likely formed from aluminum-rich sedimentary protoliths (e.g., shales) under conditions of high temperature and pressure during regional metamorphism.
