Agate, Onyx, Heliotrope, Carnelian, Chrysoprase, Mtorolite, Aventurine, Moss Agate and Lake Superior Agate are all varities of Chalcedony. Chalcedony is just Quartz & Moganite, & has the same chemical structure of Quartz which is SiO2. Jasper is also a form of Chalcedony. So to simplify things, I'm calling the beautiful things below "Chalcedony."
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