mineral
Tumbled white-gray stone, likely calcite or marble
Calcite (CaCO₃), possibly fine-grained marble (recrystallized calcite)
AI-generated identification · may be incorrectOpaque to translucent white-gray, with a waxy to vitreous luster and prominent cleavage-like planes; Mohs hardness about 3, so it scratches easily with a steel nail. The rounded shape indicates tumbling or natural abrasion, and the curved markings may be fractures or veining.
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Physical properties
Opaque to translucent white-gray, with a waxy to vitreous luster and prominent cleavage-like planes; Mohs hardness about 3, so it scratches easily with a steel nail. The rounded shape indicates tumbling or natural abrasion, and the curved markings may be fractures or veining.
Formation & geological history
Calcite forms in sedimentary limestones, hydrothermal veins, and cavities; marble forms when limestone undergoes metamorphism. Precise age and locality cannot be determined from the photograph.
Uses & applications
Used for cement, lime, aggregate, building stone, and ornamental objects; clear calcite varieties are collectible, while marble is widely used in architecture and sculpture.
Geological facts
A diagnostic test is vigorous fizzing with dilute hydrochloric acid or household vinegar, especially on a freshly scratched surface; vinegar may react slowly. It is not possible to confirm calcite versus marble visually alone.
Field identification & locations
Common worldwide, including limestone and marble regions. Check for strong acid reaction, low hardness, and rhombohedral cleavage; do not confuse it with harder quartz, which does not fizz and scratches glass.
