metamorphic
Garnet-bearing metamorphic rock, likely mica schist
Biotite–garnet schist; commonly includes quartz, feldspar, biotite, and almandine garnet
AI-generated identification · may be incorrectTypically medium- to coarse-grained, dark brown/black and sparkly, with reddish garnet crystals and flaky mica; Mohs hardness is about 2.5–7 depending on mineral, with mica schistosity and garnet’s lack of cleavage. The attached pale gray-white crystals may be quartz or feldspar.
Identified More metamorphic →
Explore Garnet-bearing metamorphic rock, likely mica schist in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically medium- to coarse-grained, dark brown/black and sparkly, with reddish garnet crystals and flaky mica; Mohs hardness is about 2.5–7 depending on mineral, with mica schistosity and garnet’s lack of cleavage. The attached pale gray-white crystals may be quartz or feldspar.
Formation & geological history
Formed when shale or another clay-rich sediment was subjected to regional heat and pressure during mountain building, commonly during the Paleozoic or Precambrian. Garnet grew during metamorphic recrystallization.
Uses & applications
Used mainly as a decorative stone, lapidary material, and teaching or collecting specimen; rarely used structurally because schist splits along foliation.
Geological facts
Garnet-bearing schists record metamorphic pressure-temperature conditions and can indicate medium- to high-grade metamorphism. Garnet composition is often almandine-rich, with formula Fe₃Al₂(SiO₄)₃.
Field identification & locations
Identify it by visible foliation, glittering mica flakes, and embedded reddish garnets; quartz is glassy and feldspar is commonly blocky and pale. Common in metamorphic belts worldwide, including the Appalachians, New England, Scandinavia, and the Alps.
More like this
