mineral
Iolite
Cordierite (Mg2Al3(AlSi5O18))
AI-generated identification · may be incorrectHardness of 7 to 7.5 on the Mohs scale, distinct violet-blue color with strong pleochroism, vitreous luster, and poor cleavage.
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Physical properties
Hardness of 7 to 7.5 on the Mohs scale, distinct violet-blue color with strong pleochroism, vitreous luster, and poor cleavage.
Formation & geological history
Forms in aluminium-rich metamorphic rocks such as hornfels and gneisses through regional or contact metamorphism.
Uses & applications
Used primarily as a gemstone in jewelry and historically as a navigational aid due to its strong polarization properties.
Geological facts
Also known as the Viking's compass, ancient mariners used iolite to locate the sun on overcast days by viewing it through the stone.
Field identification & locations
Identified by its characteristic violet-blue hue and strong pleochroism, commonly found in localities like India, Sri Lanka, and Brazil.
