metamorphic
Water-worn blue-gray pebble, likely slate or fine-grained metamorphic rock
Indeterminate from appearance; possibly slate (low-grade metamorphosed shale)
AI-generated identification · may be incorrectSmooth, rounded, blue-gray surface with faint pale banding and a dark fracture. Slate is typically very fine-grained, dull to mildly silky, and about 3–4 on the Mohs scale; the specimen’s composition and cleavage cannot be confirmed visually.
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Physical properties
Smooth, rounded, blue-gray surface with faint pale banding and a dark fracture. Slate is typically very fine-grained, dull to mildly silky, and about 3–4 on the Mohs scale; the specimen’s composition and cleavage cannot be confirmed visually.
Formation & geological history
If slate, it formed when shale was compacted and weakly metamorphosed; its age depends on the source formation. The rounded shape suggests prolonged transport and abrasion by water.
Uses & applications
Likely a decorative or collected pebble; slate is also used for roofing, paving, and boards.
Geological facts
Blue-gray color and subtle layers are consistent with slate, but similar-looking stones include phyllite and fine-grained volcanic rocks.
Field identification & locations
Look for very fine grains and flat, parallel splitting surfaces to support a slate identification. Water-worn pebbles occur in streams and on beaches worldwide; a definitive identification may require examining a fresh break.
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