mineral
Ruby / Red Tourmaline
Corundum (Al2O3) or Elbaite (Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)4)
Hardness of 9 (Ruby) or 7-7.5 (Tourmaline) on the Mohs scale. Color is vivid red to pinkish-red. Luster is vitreous to adamantine. Crystal structure is trigonal. Specific gravity ranges from 3.0 to 4.0 depending on the specific mineral species.
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Physical properties
Hardness of 9 (Ruby) or 7-7.5 (Tourmaline) on the Mohs scale. Color is vivid red to pinkish-red. Luster is vitreous to adamantine. Crystal structure is trigonal. Specific gravity ranges from 3.0 to 4.0 depending on the specific mineral species.
Formation & geological history
Formed in metamorphic or igneous environments such as marble deposits, pegmatites, or alluvial placers over millions of years through high-pressure and high-temperature geological processes.
Uses & applications
Used primarily in fine jewelry, as gemstone specimens for collectors, and historically in laser technology (synthetic ruby).
Geological facts
Red corundum is classified as ruby, while other color varieties of corundum are called sapphires. Chromium impurities are typically what give these stones their vibrant red color.
Field identification & locations
Identify by its distinctive crystal habit, vitreous luster, and high hardness (can easily scratch glass and quartz). Commonly found in regions like Myanmar, Madagascar, Mozambique, and various pegmatite fields worldwide.
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