metamorphic

Tumbled gray stone, likely slate or fine-grained metamorphic rock

Probable slate/phyllite; composition mainly quartz, mica, and feldspar

AI-generated identification · may be incorrect

Dark gray, fine-grained, subdued silky-to-dull luster with pale foliation or mineral veins; likely Mohs hardness 3–6, depending on mica content. The smooth rounded surface indicates natural water wear or tumbling; crystal grains are too fine to see clearly.

Identified September 2, 2026More metamorphic →

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At a glance

Common name: Tumbled gray stone, likely slate or fine-grained metamorphic rock
Scientific name: Probable slate/phyllite; composition mainly quartz, mica, and feldspar
Category: metamorphic
Identified: September 2, 2026
Method: Standard

AI Estimated Value

About $1–$10 as a common tumbled specimen; higher only if unusually attractive, locality-labeled, or confirmed as a collectible material.

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

Slate and phyllite form when shale undergoes low-grade metamorphism, commonly during mountain building; ages vary widely from Paleozoic to Precambrian. The pale streaks may be quartz veins or foliation surfaces.

Uses & applications

Used for roofing, flooring, paving, writing slates, landscaping, and inexpensive polished-stone collections; this specimen has little jewelry value.

Geological facts

Its layered fabric can split along cleavage, unlike most massive igneous rocks. Phyllite typically has a shinier, wavier surface than slate, but a photograph cannot reliably distinguish them.

Field identification & locations

Look for planar layering, fine grain, gray-to-black color, and splitting along foliation; quartz-rich streaks are common. Common sources include metamorphic belts worldwide, especially Wales, the northeastern United States, and the Appalachians.