Other

Cordylite Group

Corundum (Ruby)

Hardness: 9

Cubic Zirconia

Hardness: 8 - 8.5

Cuprobismutite Homologous Series Group

Cylindrite Group

D'ansite Group

Dalyite Group

Deerite-howieite Group

Delafossite Group

Demantoid Garnet

Hardness: 6.5 - 7

Dendrite Rock

Dendritic Limestone

Hardness: 3

Devilline Group

Dianite

Hardness: 6 - 7

Diaspore Group

Djerfisherite Group

Dolomite Group

Donnayite Group

Dresserite Group

Dufrénite Group

Dugganite Group

Dumortierite

Hardness: 7

Dumortierite Supergroup

Enamel

Hardness: 5.5-6.5

Epidote Supergroup

Epsomite Group

Ericssonite Group

Ettringite Group

Euchlorine Group

Eudialyte group

Euxenite Group

Fairfieldite Group

Fake Colored Stone

Fake Emerald

Fedorite Group

Feldspar Group

Feldspathoid Group

Fibroferrite Group

Fillowite Group

Fleischerite Group

Fluorite Group

Foordite Group

Fossil

Fossil Bone

Hardness: Variable

Fossil Coral

Hardness: 6.5-7

Fossiliferous Limestone

Hardness: 3

Fossilized Bone

Hardness: 4-7

Fossilized Coral

Hardness: 3-4

Fossilized Tooth

Hardness: 5-7

Francevillite Group

Franckeite Group

Franconite Group

Freieslebenite Group

Fruit Jasper

Hardness: 3 - 4

Gadolinite Group

Gainesite Group

Galena Group

Galkhaite Group

Ganophyllite Group

Garnet (Pyrope)

Hardness: 7 - 7.5