Chlorastrolite, see Preh-nite.
Chloromelanite, see Jade.
Chlorophane, see Pluo-rite.
Chlorospinel, see Spinel.
Chondroite.
Chromic iron.
Chrysoberyl.
Chrysocolla.
Chrysolite, see Olivine.
Chrysolite (Oriental), see Chrysoberyl.
Chrysoprase, see Quartz.
Cinnamon stone, see Garnet.
Citrine quartz, see Quartz.
Coal.
Cobaltite.
Cobrastone, see Fluorite.
Colophonite, see Garnet.
Congo emerald, see Diop-tase.
Coral, see Carbonate of Lime.
Cornelian, see Quartz.
Corundum.
Crocidolite.
Cymophane, see Chrysoberyl.
Cyprine, see Vesuvianite.
Damourite.
Datolite.