mineral
Banded calcite (onyx marble)
Calcite, CaCO₃; commonly sold as “honey onyx” or “Pakistan onyx”
AI-generated identification · may be incorrectCream-to-brown translucent, finely banded material with pearly to vitreous luster; Mohs hardness 3, rhombohedral calcite crystals, perfect rhombohedral cleavage, and specific gravity about 2.7. The visible parallel layers are characteristic of calcite deposited in veins or caves.
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Physical properties
Cream-to-brown translucent, finely banded material with pearly to vitreous luster; Mohs hardness 3, rhombohedral calcite crystals, perfect rhombohedral cleavage, and specific gravity about 2.7. The visible parallel layers are characteristic of calcite deposited in veins or caves.
Formation & geological history
Forms when carbonate-rich groundwater precipitates calcite in cavities, hot springs, or veins; most commercial material is geologically young compared with bedrock and is quarried especially in Pakistan, Afghanistan, Iran, Mexico, and Turkey. It is technically banded calcite, not true silica onyx.
Uses & applications
Used for ornamental carving, tiles, countertops, bookends, lamps, and polished specimens; it is too soft and cleavage-prone for most durable jewelry. Common polished pieces typically sell for $10–$60, with larger or especially translucent specimens around $100–$300.
Geological facts
Calcite effervesces strongly with dilute hydrochloric acid or vinegar, unlike quartz-based agate. It may scratch easily with a steel knife and can show strong optical doubling through clear areas.
Field identification & locations
Identify by its softness, layered cream-brown appearance, rhombohedral cleavage, and acid reaction; avoid confusing it with harder agate or marble. Common collecting and commercial localities include Pakistan, Mexico, and Turkey.
