Garnet
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Garnets are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives.
A sample showing the deep red color garnet can exhibit.
Crystal structure of pyrope garnet: White spheres are oxygen; black is silicon; blue is aluminium; and red is magnesium.
Same view, with ion sizes reduced to better show all ions
Scapolite
Videos
The scapolites are a group of rock-forming silicate minerals composed of aluminium, calcium, and sodium silicate with chlorine, carbonate and sulfate. The two endmembers are meionite and marialite. Si
Marialite, a component of scapolite, from Tanzania at the National Museum of Natural History