metamorphic
Rounded yellow-green pebble, likely serpentine or quartzite
Provisional: serpentinite/serpentine-rich rock; alternatively iron-stained quartzite
AI-generated identification · may be incorrectPale olive-yellow, opaque, fine-grained, and smoothly water-worn with a dull to weak waxy luster. Hardness is likely Mohs 3–4 for serpentine or about 7 for quartzite; cleavage is absent or indistinct, and the image is insufficient for firm identification.
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Physical properties
Pale olive-yellow, opaque, fine-grained, and smoothly water-worn with a dull to weak waxy luster. Hardness is likely Mohs 3–4 for serpentine or about 7 for quartzite; cleavage is absent or indistinct, and the image is insufficient for firm identification.
Formation & geological history
If serpentine, it formed when ultramafic mantle rock altered hydrothermally, commonly during ocean-floor metamorphism; if quartzite, it formed by metamorphism of sandstone. A geological age cannot be determined visually.
Uses & applications
Small pieces are used as curios, cabochons, or tumbled stones; serpentine may be used decoratively, while quartzite is used as aggregate and building stone. Avoid cutting unknown serpentine because some varieties may contain asbestos-forming minerals.
Geological facts
The rounded shape indicates transport by water or wave action. A steel scratch test can distinguish candidates: serpentine is scratched by steel, whereas quartzite generally scratches glass.
Field identification & locations
Common possibilities occur in serpentinite belts, stream gravels, beaches, and metamorphic terrains worldwide; inspect for green veining, slick waxy surfaces, or quartz-like granular texture. Estimated value: $1–$10 as a common pebble, or $10–$30 if attractive and polished.
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