metamorphic
Pyrite-bearing dark slate or phyllite
Likely pyrite (FeS₂) disseminated in fine-grained slate/phyllite; exact host rock cannot be confirmed from the photo
AI-generated identification · may be incorrectDark, fine-grained, foliated host with scattered brassy metallic flecks. Pyrite is Mohs 6–6.5, cubic, and metallic; the host rock is much softer and splits along foliation.
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Physical properties
Dark, fine-grained, foliated host with scattered brassy metallic flecks. Pyrite is Mohs 6–6.5, cubic, and metallic; the host rock is much softer and splits along foliation.
Formation & geological history
The host likely formed when clay-rich sediment was compacted and metamorphosed at low grade; pyrite formed or crystallized within it. The specimen’s age and locality are unknown.
Uses & applications
Mostly a collecting specimen; slate and phyllite are used for roofing, paving, and decorative stone, while pyrite is collected but rarely an ore in this form.
Geological facts
The brassy flecks resemble pyrite, often called fool’s gold; visual identification alone cannot rule out another sulfide mineral.
Field identification & locations
Look for thin, planar splitting and brassy grains that are opaque and brittle; pyrite commonly leaves a dark streak, unlike gold’s yellow streak. A scratch or streak test can help confirm it.
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