metamorphic
Graphite-bearing quartz-mica schist
Graphite-rich quartz–mica schist; primarily quartz (SiO₂), muscovite/biotite, and graphite (C)
AI-generated identification · may be incorrectHardness is typically 2–3 for graphite, 6–7 for quartz; dark gray to silvery black, with vitreous quartz and distinctly greasy/metallic graphite luster. Foliated, flaky texture and irregular quartz-rich bands are visible; cleavage is strong in mica and graphite, while quartz lacks cleavage.
Identified More metamorphic →
Explore Graphite-bearing quartz-mica schist in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness is typically 2–3 for graphite, 6–7 for quartz; dark gray to silvery black, with vitreous quartz and distinctly greasy/metallic graphite luster. Foliated, flaky texture and irregular quartz-rich bands are visible; cleavage is strong in mica and graphite, while quartz lacks cleavage.
Formation & geological history
Formed when carbonaceous shale or mudstone underwent regional metamorphism, causing recrystallization, mica alignment, and graphite formation. Exact age cannot be determined from an image; such rocks occur in Precambrian to younger metamorphic belts.
Uses & applications
Used locally as decorative stone, building aggregate, or a source of graphite when sufficiently rich; mostly collected as a mineralogical specimen rather than used in jewelry.
Geological facts
The bright, easily smudged or pencil-like flakes are diagnostic of graphite, whereas the white translucent material is quartz. A streak test on unglazed porcelain can help distinguish graphite from metallic sulfides.
Field identification & locations
Common in high-grade metamorphic terrains worldwide, including Canada, the United States, Brazil, Madagascar, India, and Scandinavia. Test whether dark flakes mark paper and whether quartz grains scratch glass; avoid assuming the shiny areas are galena without a streak and density test.
More like this
