common minerals

Tables of Common Minerals


Some Non-metallic minerals and their properties (table)
Some metallic minerals and their properties (table)
Identification Flowchart of Common Minerals (separate file 300k)

see also... how to identify minerals based on their physical properties



Non-metallic Minerals and their 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

CaSO
42H2O

crystalline,
granular
vitreous

2.3

colourless, white

white

2

n/a


evaporites

plaster-of
-paris, plasterboard
 ie. Gyproc

Satin spar
gypsum

CaSO4
2H2O

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[Si6-5Al2
-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

sub-
transparant
 to
translucent

orthoclase
 is
named
after it's 2 cleavages
at
right angles:

ortho=right
klastos
=breaks, 

common
rock forming
mineral in
igneous, 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

sub-
transparant
 to
translucent

plagioclase
 is named after its 2 cleavages
at almost
right
angles:

plagio=almost
klastos=breaks

common
rock forming
 mineral in
igneous, 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

sub-
transparant
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
igneous, 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)

rhombo-
dodecahedral, dodecahedral and tetra-
hexahedral 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
paper is
 a red
abraisive
paper
used on
wood).

Malachite

Cu2[(OH)
2CO3]

crypto-
crystalline
dull

4.0

emerald green, or other shades of green

light green,

good

4.0


a weathering
product of
copper
deposits
Chrysocolla

Cu4H4
[(OH)8Si4
O10]

crypto-
crystalline
dull

2.0 - 2.3

blue-green

pale green or blue-green

none

2 - 4


in oxidation
zones in
copper
ore deposits



Metallic Minerals and their Properties


NAME
FORMULA
HABIT LUSTRE
S.g.
USUAL COLOUR/
STREAK
HARDNESS
CLEAVAGE
OTHER
PROPERTIES
OCCURRENCE
USES
Galena

PbS

cubic crystals metallic

7.5

silver-grey

grey-black

2.5

3; perfect cubic cleavage


vein mineral, often with calcite, fluorspar and barites

cheif source of lead (Pb).

Haematite

Fe2O3

reniform aggregate habit earthy

5

Red-brown

red-brown

5.5 to 6.5

2 poor cleavages

sub-conchoidal or uneven fracture often in limestones as a relacement minerals, also in metamorfphic deposites, ironstones and as both thin veins and cement in sandstones eg. the New Red Sandstone

iron ore and used as a pigment in paint 'Red Ochre'

Pyrite

FeS2

cubic crystals, or as pentagonal dodecahedral crystals.  Also as nodules with an internal structure of radiating needles, also as crystalline masses metallic

5.0

brass-yellow

black

6 - 6.5

no cleavage

cubic crystals often have striated faces,
conchoidal fracture, 
sparks when struck with geological hammer 
pyrite = fire mineral.
smells sulphurous when rubbed on a streak plate
occurs as free crystals or nodules in coal, clay and shales, also in veins

formerly source of sulphur, used to make sulphuric acid (native sulphur now main source).

Sphalerite (aka zinc blende, black jack)

ZnS

usually massive aggregates, also tetrahedral crystals resinous, sometimes brilliant or adamantine on fresh surfaces

4.0

brown or black

pale yellow

3.5 - 4

perfect cleavage in 6 directions

smells sulphurous when rubbed on a streak plate vein mineral

chief source of [non-corrosive] zinc, used for galvanisation of iron

Chalcopyrite

CuFeS2

octohedral and tetrahedral crystals metallic

4.1 - 4.3

brass-yellow

black or greenish-black

3.5 - 4.0

indistinct


ore mineral

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