mineral
Chiastolite
Andalusite variety Chiastolite (Al2SiO5)
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, grayish-white to reddish-brown color with a distinctive dark carbonaceous cross pattern, vitreous to dull luster, and orthorhombic crystal system.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, grayish-white to reddish-brown color with a distinctive dark carbonaceous cross pattern, vitreous to dull luster, and orthorhombic crystal system.
Formation & geological history
Forms through regional metamorphism of argillaceous sediments rich in organic matter, typically under moderate temperatures and low pressures.
Uses & applications
Used as a talisman, in ornamental jewelry, and as a popular specimen for mineral collectors due to its natural cross inclusion.
Geological facts
The characteristic dark cross is formed by the selective trapping of carbon impurities during crystal growth in metamorphic schists.
Field identification & locations
Easily identified by the striking dark cross pattern visible in cross-section. Commonly found in metamorphic rocks in Spain, Russia, the USA, and Australia.
