non-metallic minerals and their characteristic properties, for identification

Some

Minerals and their
Characteristic Properties

N.B. most (if not all) minerals with colour listed as 'colourless' may
be tinted almost any colour by the presence of trace impurities.

NAME FORMULA	HABIT	LUSTRE S.g.	USUAL COLOUR/ STREAK	HARDNESS CLEAVAGE	OTHER PROPERTIES	OCCURRENCE USES
Calcite CaCO₃	rhombohedral, dog tooth and nail head crystals	vitreous 2.7	colourless or white white	3 3 perfect, rhombohedral	effervesces vigorously in dil. HCl. double refraction of images viewed throught it	as limestone, in veins, as stalactites, stalagmites lime fertilizer, cement, flux in steel industry
Selenite gypsum CaSO₄2H₂O	lozenge crystals, often fishtail twins	vitreous 2.3	colourless, white white	2 1 perfect, parallel to crystal faces		evaporites and free-growing in clays plaster-of-paris, plasterboard ie. Gyproc
Alabaster gypsum CaSO₄2H₂O	crystalline, granular	vitreous 2.3	colourless, white white	2 n/a		evaporites plaster-of-paris, plasterboard ie. Gyproc
Satin spar gypsum CaSO₄2H₂O	fibrous	vitreous 2.3	colourless, white white	2 n/a		evaporites plaster-of-paris, plasterboard i.e.. Gyproc
Halite (rock salt) NaCl	cubic crystals, with hollow stepped faces	vitreous 2.2	colourless, white white	2 - 2.5 3 good, cubic	tastes of salt, soluble in water (so clean it in petrol)	evaporite, playa lake deposit food processing, washing soda
Quartz SiO₂	elongated hexagonal prisms capped by pyramids, or crystalline granular	vitreous 2.65	colourless in rock crystal - see guide to properties for other varieties white	7 none	horizontal striations on crystal faces, conchoidal fracture	as sand and sandstone, in veins, as geodes, constituent in many igneous and metamorphic rocks microchips, gemstone. concrete and glass making (as sand)
Barite BaSO₄	tabular crystals, reticulate crystals, or radiating bladed 'cockscomb' structures in crystalline form	vitreous 4.5	colourless, white white	2.5 - 3.5 3 good, 1 horizontal (basal), 2 vertical (at 90 degrees to basal)	heaviest vitreous mineral at s.g.4.5	vein mineral used in paint and paper, and as a drilling mud in the oil industry
Biotite mica K₂(Mg,Fe²⁺)_6-4(Fe³⁺ Al,Ti)_0-2[Si_6-5Al_2-3O₂₀] OH,F)₄	foliaceous, platey, pseudo-hexagonal crystals	pearly 3.0	brown, black white	2.5 - 3 1 perfect basal		a common rock forming mineral in sedimentary, metamorphic and igneous rocks used for furnace windows heat resistant formica and as glitter in a wide range of products.
Muscovite mica K₂Al₄[Si₆Al₂O₂₀](OH,F)₄	foliaceous, platey, pseudo-hexagonal crystals	pearly 3.0	silvery-white (named after Moscow in 'White Russia' white	2 - 2.5 1 perfect basal		a common rock forming mineral in sedimentary, metamorphic and igneous rocks used for furnace windows heat resistant formica and as glitter in a wide range of products.
Fluorite, Blue John CaF₂	cubic crystals or as crystalline masses	vitreous, sometimes a very slightly greasy or watery appearance 2.7	colourless, blue & yellow as blue john variety white	4 4 perfect octohedral:- cleavage planes cut across corners of 6-sided cubic crystals to leave 8-sided octohedral cores.	blue john is coloured by oil impurities and is only found in situ at Mam Tor in Derbyshire, UK	vein mineral semi-precious gemstone as blue john (from French; bleu-blue jaune-yellow). Also used as flux in steel smelting
Orthoclase feldspar (complex framework silicate)	prismatic, tabular or rectangular crystals	vitreous to pearly about 2.6	colourless (may be cloudy), white, pink or pale red, other pale colours also white	6 (a moh's scale mineral) 2 cleavages at 90 degrees	subtransparatn to translucent orthoclase is named after it's 2 cleavages at right angles: ortho=right klastos=breaks,	common rock forming mineral in igneouc, metamorphic and sedimentary rocks used in vitreous chinaware and as an abraisive in scouring powders.
Plagioclase feldspar (complex framework silicate)	prismatic, tabular or rectangular crystals	vitreous to pearly about 2.7	white or grey to grey-blue or other pale colours white	6 - 6.5 2 cleavages at almost 90 degrees	subtransparatn to translucent plagioclase is named after its 2 cleavages at almost right angles: plagio=almost klastos=breaks	common rock forming mineral in igneouc, metamorphic and sedimentary rocks used in vitreous chinaware and as an abraisive in scouring powders.
Oligoclase feldspar (complex framework silicate)	prismatic, tabular or rectangular crystals	vitreous to pearly about 2.6	white or pale colours white	2 cleavages at almost 90 degrees 6 - 6.5	subtransparatn to translucent oligoclase is named after it's cleavages at a few degrees from a right angle: oligo=a few klastos=breaks	common rock forming mineral in igneouc, metamorphic and sedimentary rocks used in vitreous chinaware and as an abraisive in scouring powders.
Olivine FeMgSiO₄	tabular crystals or granular crystalline masses	vitreous 2.5 - 3.5 (more often ~3.5)	green, may also be yellow or brown white	1 poor cleavage, cracks on what appears to be second cleavage plane; actually a sub-parallel fracture 6 - 7		occurs in basic and ultrabasic igneous rock, best crystals occur in olivine-peridotite gemstone
Garnet (a group of Fe,Ca,Al,Cr,Mn & Mg, silicate minerals)	rhombododecahedral, dodecahedral and tetrahexahedral crystals, also as angular fragments	vitreous 3.6 - 4.3	deep red, crimson, purple, brown, black, olive, greens, pink, yellow white	no cleavage 7 - 7.5 (except gossular variety, which may be as low as 6.5)		a dense mineral formed in high pressure/temperature condition in metamorphic rocks used as a gemstone and as an abraisive (garnet parer is a red abraisive paper used on wood).
Malachite Cu₂[(OH)₂CO₃]	cryptocrystalline	dull 4.0	emerald green, or other shades of green light green,	good 4.0		a weathering product of copper deposits
Chrysocolla Cu₄H₄[(OH)₈Si₄O₁₀]	cryptocrystalline	dull 2.0 - 2.3	blue-green pale green or blue-green	none 2 - 4		in oxidation zones in copper ore deposites