sedimentary
Pink Banded Onyx (Mexican Onyx / Calcite)
Calcite (CaCO3) - microcrystalline calcium carbonate
Hardness: 3 on Mohs scale (soft); Color: Cream, white, and swirls of salmon pink; Luster: Vitreous to waxy (when polished); Structure: Hexagonal/Trigonal; Cleavage: Perfect rhombohedral.
- Hardness
- 3 on Mohs scale (soft)
- Color
- Cream, white, and swirls of salmon pink
- Luster
- Vitreous to waxy (when polished)
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Physical properties
Hardness: 3 on Mohs scale (soft); Color: Cream, white, and swirls of salmon pink; Luster: Vitreous to waxy (when polished); Structure: Hexagonal/Trigonal; Cleavage: Perfect rhombohedral.
Formation & geological history
Formed in caves (stalagmites/stalactites) or near cold spring water through the chemical precipitation of calcium carbonate. This material is often associated with the Cenozoic era or more recent geological formations.
Uses & applications
Primarily used for ornamental carvings, figurines, bookends, vases, lamps, and architectural accents like floor tiles or bathroom vanities.
Geological facts
Despite its trade name 'Onyx', this is geologically a form of Calcite/Aragonite, not true chalcedony onyx. It is prized for its translucency when held up to a light source.
Field identification & locations
Identify by its softness (can be scratched by a steel copper penny or knife) and its reaction (bubbling) to dilute hydrochloric acid. It is commonly sourced from Mexico and Pakistan. For collectors, look for smoothness and vibrant banding.
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