metamorphic

Quartz-veined dark metamorphic rock

Likely quartz-bearing hornfels, amphibolite, or altered basalt; exact identification requires a fresh surface and tests

AI-generated identification · may be incorrect

Dark gray, fine- to medium-grained matrix with white to cream, glassy quartz-rich veins or patches; quartz is Mohs 7 with vitreous luster, while the matrix may be harder than steel and lacks obvious cleavage. The cream material could also include calcite or weathered feldspar.

Identified September 5, 2026More metamorphic →

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At a glance

Common name: Quartz-veined dark metamorphic rock
Scientific name: Likely quartz-bearing hornfels, amphibolite, or altered basalt; exact identification requires a fresh surface and tests
Category: metamorphic
Identified: September 5, 2026
Method: Standard

AI Estimated Value

About $5–$25 as an unattributed hand specimen; potentially $20–$75 if locality, mineral identity, or aesthetics are documented.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Probably formed by metamorphism or hydrothermal alteration of a mafic volcanic rock, with later silica-rich fluids filling fractures; age depends on locality and cannot be determined visually.

Uses & applications

Primarily a collecting specimen or field sample; similar tough rocks may be used as crushed aggregate or decorative stone, but this piece has little commercial value.

Geological facts

The irregular white infill suggests mineralized fractures rather than a fossil. Acid testing, streak, and a close examination of crystal grains would distinguish quartz from calcite and refine the rock name.

Field identification & locations

Commonly found in metamorphic belts, volcanic terrains, and hydrothermal zones worldwide. Look for quartz that scratches glass and does not fizz in dilute hydrochloric acid; calcite fizzes and is softer.