SiO₂ - Mohs Hardness: 7. In antiquity, as well as in the Middle Ages, people believed that the cosmos was reflected in gemstones. The amethyst is assigned to the planet Neptune. The esoteric movement revived the ancient belief and the gem industry made it another marketing tool to promote certain gems.
UT Department of Environmental Sciences
The University of Toledo
Digital Initiatives, University of Toledo Libraries
environmental sciences; virtual exhibitions
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