Stone	Formula	Group	Other Information
	Black Sapphire	Al2O3	Oxides	black/green-due to Fe & titanium impurities-form of corundum
	Blue John	CaF2	Halides	colourless-form of flourite-found in peak district
	Blue Quartz	SiO2 with inclusions	Oxides	blue-contains many inclusions-aka sapphire quartz
	Bornite	Ca5FeS4	Sulphides	brown-aka peacock ore-rainbow colours due to tarnishing
	Bowenite	(Mg,Fe)3 SiO5(OH)4	Silicates	variable colour-member of serpentine group-like nephrite
	Brazilianite	NaAl3(PO4)2 (OH)4	Phosphates	yellow-rare-discovered recently in 1944
	Breccia	-	Sedimentary	variable colour-angular rock lumps set in a fine grained base
	Calcite	CaCO3	Carbonates	colourless-found in all limestones
	Cannel Coal	-	Sedimentary	black-made from veg. matter-formed in anaerobic conditions
	Carnelian	SiO2	Oxides	red/orange-variety of chalcedony-colour due to Fe oxides
	Celestine	SrSO4	Sulphates	colourless-source of strontium-forms by evap. of salt water
	Celestite	SrSO4	Sulphates	sky blue-aka strontium sulphate
	Cerussite	PbCO3	Carbonates	often colourless or white-source of lead
	Chalcedony	SiO2	Oxides	variable colour-variety of quartz-forms=sard,agate,jasper
	Chalcopyrite	CuFeS2	Sulphides	yellow-aka copper pyrite-similar to pyrite
	Charoite	K5Ca8Si18 O46(OH)3 3(H2O)	Silicates	found only in one location-near the charo river in Russia
	Chiastolite	-	Metamorphic	a hornfel-variety of andalusite-contains quartz and mica
	Chrome Diopside	CaMgSi2O6	Silicates	colourless-green due to presence of Cr oxides
	Chromite	FeCrO4	Oxides	black-source of chromium
	Chrysocolla	Ca2H2Si12 O5(OH)4	Silicates	green/blue-forms in Cu deposits
	Chrysoprase	SiO2	Oxides	green-variety of chalcedony-green due to nickel silicate
	Citrine	SiO2	Oxides	yellow/brown-form of quartz-colour due to presence of Fe
	Colemanite	Ca2B6 O115H2O	Borates	colourless-source of boron-formed in playas
	Copal	-	Organic	yellow/red-from resins secreted by some tropical trees
	Coral	CaCO3	Organic	formed from skeletal remains of polyps
	Cordierite	(Mg,Fe)2 Al4Si5O18	Silicates	blue-aka iolite-blue due to presence of Fe Corundum Al2O3 Oxides
	Corundum	Al2O3	Oxides	colourless-forms include ruby and sapphire

Chemical Symbols