mineral

Weathered quartz-rich stone, possibly chalcedony or calcite

Likely microcrystalline quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing

AI-generated identification · may be incorrect

Tan to cream, opaque, rough and locally waxy/glassy luster with possible crystalline texture. Quartz hardness 7, no cleavage; calcite hardness 3, prominent rhombohedral cleavage and effervesces in dilute hydrochloric acid.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

May be a naturally weathered mineral fragment from a sedimentary or hydrothermal vein; the specimen’s geological age and source cannot be determined from the image.

Uses & applications

Small pieces have little industrial or jewelry value unless confirmed as attractive chalcedony, agate, or a collectible mineral; quartz is widely used in glass, electronics, and abrasives, while calcite is used in cement and lime.

Geological facts

Its irregular rounded shape and surface staining are consistent with weathering. A hardness test and acid test would distinguish the two leading possibilities.

Field identification & locations

Commonly found in gravel, soils, eroded veins, and sedimentary rocks worldwide. Scratch with a steel knife or glass, inspect for cleavage, and test a hidden spot with dilute acid.