mineral
Tumbled ruby-bearing corundum
Corundum (Al₂O₃), likely ruby variety
AI-generated identification · may be incorrectHardness 9 Mohs; pinkish-red to purplish-red, with a dull to vitreous luster and massive, non-cleavable crystal structure. Dark inclusions and uneven coloration suggest low-grade ruby in corundum rather than gem-quality material.
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Physical properties
Hardness 9 Mohs; pinkish-red to purplish-red, with a dull to vitreous luster and massive, non-cleavable crystal structure. Dark inclusions and uneven coloration suggest low-grade ruby in corundum rather than gem-quality material.
Formation & geological history
Forms in aluminum-rich, silica-poor metamorphic rocks such as marble and mica schist, commonly during regional metamorphism; specimens may be hundreds of millions to over a billion years old. The rounded shape appears tumbled or naturally water-worn.
Uses & applications
Used primarily as an abrasive and, when transparent and strongly colored, as a gemstone; this opaque specimen is mainly suitable for collecting or lapidary work.
Geological facts
Ruby and sapphire are color varieties of corundum; chromium commonly produces ruby’s red color. Corundum is second only to diamond in natural mineral hardness.
Field identification & locations
Common sources include Myanmar, Mozambique, Sri Lanka, Tanzania, India, and Madagascar. Confirm with hardness testing, streak testing, and ideally refractive-index or chemical analysis; visual identification alone is uncertain.
