mineral
Tumbled magnesite
Magnesite (MgCO₃), likely compact or veined magnesite
AI-generated identification · may be incorrectTypically opaque white to cream with gray-brown veining, waxy to dull luster, and a smooth tumbled surface; Mohs hardness 3.5–4.5, trigonal crystal structure, and perfect rhombohedral cleavage. Specific gravity is about 3.0–3.1.
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Physical properties
Typically opaque white to cream with gray-brown veining, waxy to dull luster, and a smooth tumbled surface; Mohs hardness 3.5–4.5, trigonal crystal structure, and perfect rhombohedral cleavage. Specific gravity is about 3.0–3.1.
Formation & geological history
Forms when magnesium-rich rocks or hydrothermal fluids alter ultramafic rocks and carbonate sediments; deposits range from Precambrian to recent geological ages. The specimen has been shaped and polished by human processing.
Uses & applications
Used as a magnesium ore, refractory material, and industrial carbonate; attractive pieces are sold as inexpensive lapidary material, beads, and carvings.
Geological facts
Magnesite is commonly dyed to imitate turquoise and may be marketed as “white turquoise,” though that trade name is misleading. Brown veining can result from iron oxides or matrix minerals.
Field identification & locations
Identify it by its soft, chalky-to-waxy feel, white color, moderate weight, and strong reaction to dilute hydrochloric acid when powdered or freshly scratched. Common sources include Austria, Brazil, China, Greece, and the United States.
