metamorphic

Graphite-bearing quartz-mica schist

Graphite-rich quartz–mica schist; primarily quartz (SiO₂), muscovite/biotite, and graphite (C)

AI-generated identification · may be incorrect

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.

Identified August 11, 2026More metamorphic →

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Physical properties

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.