metamorphic

Calcite-rich limestone (likely crystalline limestone/marble)

Calcite, CaCO₃; likely recrystallized carbonate rock

AI-generated identification · may be incorrect

White to tan, translucent patches, pearly to vitreous luster, coarse interlocking crystals, and irregular fracture. Calcite has Mohs hardness 3, perfect rhombohedral cleavage, and specific gravity about 2.71; it should effervesce strongly with dilute hydrochloric acid or vinegar, though vinegar is weaker.

Identified September 16, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely limestone recrystallized during low-grade metamorphism into marble or crystalline limestone; carbonate rocks commonly formed in ancient shallow marine settings, with exact age indeterminable from the photograph.

Uses & applications

Used for lime and cement, aggregate, building stone, and decorative slabs; attractive crystalline pieces may be collected, but this irregular specimen has modest commercial value.

Geological facts

Calcite is commonly mistaken for quartz, but it is much softer and reacts with acid. The cream-brown coloration likely reflects iron-oxide or clay impurities.

Field identification & locations

The image supports calcite-rich carbonate rock, but cannot reliably distinguish marble from limestone. It is geologically plausible near 9.9°N, 124.2°E in Bohol, Philippines, where uplifted and metamorphosed carbonate terrains occur; test with acid and a steel knife.