metamorphic

Yellowish calcite-rich rock, likely marble or limestone

Calcite (CaCO₃), possibly recrystallized as marble

AI-generated identification · may be incorrect

Pale yellow, translucent-to-opaque, with a sugary crystalline texture and weak vitreous/pearly luster. Calcite has Mohs hardness 3, rhombohedral cleavage, and specific gravity about 2.71; it should fizz briskly in dilute hydrochloric acid or strong vinegar if fresh.

Identified September 14, 2026More metamorphic →

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Physical properties

Formation & geological history

Likely carbonate rock formed from marine limestone; if marble, heat and pressure recrystallized the calcite during metamorphism. The Baja California region near 31.7°N, 116.6°W contains carbonate rocks and metamorphic terrains, so this is regionally plausible, though age cannot be determined from the photograph.

Uses & applications

Used as aggregate, building stone, lime/cement feedstock, and decorative material; attractive translucent pieces may be collected but this small specimen has little commercial value.

Geological facts

Yellow color commonly comes from iron staining or other trace impurities. Calcite can be distinguished from quartz by its much lower hardness and acid reaction.

Field identification & locations

Test a hidden edge with a steel nail or knife: calcite scratches easily, while quartz does not. A drop of dilute acid should effervesce; avoid testing valuable specimens. Common regional alternatives include ordinary limestone, calcite vein material, or dolomite.