mineral
Corundum (Pink Sapphire / Ruby)
Al2O3 (Aluminum Oxide)
Hardness 9 on Mohs scale, Pink color, Adamantine to vitreous luster, Hexagonal crystal system, No true cleavage, Specific gravity 3.95-4.10
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Physical properties
Hardness 9 on Mohs scale, Pink color, Adamantine to vitreous luster, Hexagonal crystal system, No true cleavage, Specific gravity 3.95-4.10
Formation & geological history
Formed in metamorphic rocks such as marbles or schists and igneous rocks like syenites. These specimens are often millions of years old and crystallize under high pressure and temperature in aluminum-rich environments.
Uses & applications
Used primarily as gemstones in jewelry; synthetic versions are used for industrial abrasives, watch bearings, and laser applications.
Geological facts
Corundum is the second hardest natural mineral known to man. When red, it is called Ruby; all other colors, like this pink specimen, are called Sapphires.
Field identification & locations
Identify by its characteristic hexagonal barrel shape and extreme hardness (will scratch glass easily). Commonly found in alluvial deposits in Madagascar, Sri Lanka, and Myanmar.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock
![Biotite Schist (Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]) — metamorphic](https://media.rock.id/9ca564b5-bc87-402b-965a-69b21f9aa6bf-thumbnail.jpg)
Biotite Schist
Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]
metamorphic