GeoChemistry

Minerals are naturally occurring, homogeneous solids formed in the Earth's crust by the inorganic forces of nature.  They posess definite chemical compositions, physical characteristics, and highly ordered atomic arrangements.  The table below contains the common minerals.  Included with the list are the chemical compositions, the color(s) most often associated with the mineral, and the crystal system possessed by the mineral.  Please note that the physical properties commonly used to identify minerals and those listed below contain a certain amount of variation in the properties found from specimen to specimen.

Explanation of terms used in table:

Crystal System Terms
hex
hexagonal
Crystal system having three axes of equal length intersecting in one plane at 60 degrees and a fourth axis of different length at 90 degrees to the plane of the other three axes.
Click to see a hexagonal lattice
iso
iosmetric
Crystal system possessing quality in measure; cubic
Click to see a simple cubic lattice
mono
monclinic
Crystal system characterized by three axes of unequal length, two of which intersect obliquely and are perpendicular to the third
Click to see a simple monoclinic lattice
ortho
orthorhombic
Crystal system characterized by three axes unequal in length and at right angles to one another
Click to see a simple orthorhombic lattice
tet
tetragonal
Crystal system in which the three axes intersect at right angles and the two horizontal axes are equal
Click to see a body centered tetragonal lattice
trig
trigonal
Crystal system having three unequal axes, equally inclined
 
Mohs' Hardness Scale
<2.5
can be scratched by a fingernail
>2.5-3
cannot be scratched by fingernail; can be scratched by a copper cent
>3-5.5
cannot be scratched by a copper cent; can be scratched by a knife
>5.5-<7
cannot be scratched by a knife; can be scratched by quartz
>7
cannot be scratched by quartz

 

 

Table of Minerals
Mineral
Composition
Color
Crystal System 
Hardness
Index of Refraction
Specific Gravity
Acanthite
Ag2S
gray-black
mono
2-2.5
-
7.3
Actinolite
Ca2(Mg,Fe)5Si8O22(OH)2
green
mono
6
1.64
3.0-3.4
Aegirine
NaFeSi2O6
dark green, brown, black
mono
6
1.82
3.6
Allanite
(Ca,Ce)3(Al,Fe)2Si3O12(OH)
brown to pitch-black
mono
5.5-6
1.70-1.81
3.5-4.2
Almandine
Fe3Al2Si3O12
red to black
iso
7-7.5
1.83
4.0-4.3
Alunite
KAl3(SO4)2(OH)6
white- red
hex
4
1.57
2.6-2.8
Amblygonite
LiAlFPO4
white, pale green, blue
trig
6
1.60
3.0-3.1
Analcime
NaAlSi2O6*H2O
colorless, white
iso
5-5.5
1.48-1.49
2.27
Anatase
TiO2
brown
tet
5.5-6
2.6
3.9
Andalusite
Al2SiO5
reddish-brown, white, gray
ortho
7.5
1.64
3.16-3.20
Andradite
Ca3Fe2Si3O12
yellow, green, brown, black
iso
7-7.5
1.89
3.8-3.9
Anglesite
PbSO4
colorless, white
ortho
3
1.88
6.2-6.4
Anhydrite
CaSO4
colorless
ortho
3-3.5
1.58
2.89-2.98
Anthophyllite
(Mg,Fe)7Si8O22(OH)2
white, gray
ortho
5.5-6
1.61-1.71
2.85-3.2
Antimony
Sb
white to gray
hex
3-3.5
-
6.7
Antlerite
Cu3(SO4)(OH)4
dark emerald-green
ortho
3.5-4
1.74
3.88
Apatite
Ca5(PO4)3(F,Cl,OH)
green, blue, violet, brown, colorless
hex
5
1.63
3.15-3.20
Apophyllite
KCa4(Si4O10)2F*8H2O
colorless, white
tet
4.5-5
1.54
2.3-2.4
Aragonite
CaCO3
colorless, white
ortho
3.5-4
1.68
2.95
Argentite
Ag2S
black
iso
2-2.5
-
7.2-7.4
Arsenic
As
tin-white
hex
3.5
-
5.7
Arsenopyrite
FeAsS
silver-white
 mono
5.5-6
-
6.0-6.2
Atacamite
Cu2Cl(OH)3
emerald-green
ortho
3-3.5
1.86
3.75-3.77
Augite
(Ca, Na)(Mg, Fe, Al)(Si, Al)2O6
black, dark green
mono
6
1.67-1.73
3.25-3.55
Autunite
Ca(UO2)2(PO4)2*10-12H2O
lemon-yellow
tet
2-2.5
1.58
3.1-3.2
Axinite
(Ca, Fe, Mn)3Al2(BO3)(Si4O12)(OH)
clove-brown
trig
6.5-7
1.69
3.27-3.35
Azurite
Cu3(CO3)2(OH)2
azure-blue
mono
3.5-4
1.76
3.77
Barite
BaSO4
colorless, white
ortho
3-3.5
1.64
4.5
Bauxite
A mixture of Al hydroxides
yellow, brown, gray, white
-
1-3
-
2.0-2.55
Beryl
Be3Al2(Si6O18)
bluish-green, yellow, colorless
hex
7.5-8
1.57-1.61
2.65-2.8
Biotite
K(Mg, Fe)3(AlSi3O10)(OH)2
dark brown, green to black
mono
2.5-3
1.61-1.70
2.95-3
Bismusth
Bi
silver-white
hex
2-2.5
-
9.8
Boehmite
g-AlO(OH)
white, yellow, grown
ortho
3
1.65
3.0-3.1
Borax
Na2B4O5(OH)4*8H2O
colorless, white
mono
2-2.5
1.47
1.71
Bornite
Cu5FeS4
brownish-bronze
tet
3
-
5.1
Boulangerite
Pb5Sb4S11
bluish-lead-gray
mono
2.5-3
-
6.23
Bournonite
PbCuSbS3
steel-gray to black
ortho
2.5-3
-
5.8-5.9
Braunite
3Mn2O3*MnSiO3
gray to black
tet
6-6.5
-
4.7-4.8
Brochantite
Cu4SO4(OH)6
green
mono
3.5-4
1.78
4.0
Brookite
TiO2
brown to black
ortho
5.5-6
2.6
4.1
Brucite
Mg(OH)2
white, gray, green
hex
2.5
1.57
2.39
Bustamite
(Mn, Ca, Fe)SiO3
 
trig
5.5-6.5
1.67-1.70
3.3-3.4
Calaverite
AuTe2
tin-white to brass yellow
mono
2.5
-
9.4
Calcite
CaCO3
colorless, white
hex
3
1.66
2.71
Cancrinite
Na6Ca2(AlSiO4)6(CO3)2
yellow, white, pink
hex
6
1.52
2.4-2.5
Carnallite
KMgCl3*6H2O
colorless, white
ortho
2.5
1.48
1.60
Carnotite
K2(UO2)2(VO4)2*3H2O
yellow
mono
2
1.93
4-5
Cassiterite
SnO2
brown to black
tet
6-7
2.00
6.8-7.1
Celestite
SrSO4
colorless, white, pale blue
ortho
3-3.5
1.62
3.95-3.97
 
Cerussite
PbCO3
colorless, white
ortho
3-3.5
2.08
6.55
Chabazite
Ca2Al2Si4O12*6H2O
white, flesh-red
hex
4-5
1.48
2.05-2.15
Chalcanthite
CuSO4*5H2O
blue
trig
2.5
1.54
2.28
Chalcocite
Cu2S
steel-gray
ortho
2.5-3
-
5.7
Chalcopyrite
CuFeS2
brass-yellow
tet
3.5-4
-
4.1-4.3
Chlorargyrite
AgCl
pearl-gray, colorless
iso
2-3
2.07
5.5
Chlorite
Mg, Fe3(Si, Al)4O10(OH)2*(Mg, Fe)3(OH)6
green of various shades
mono
2-2.5
1.57-1.67
2.6-2.9
Chloritoid
(Fe, Mg, Mn)2(Al, Fe) Al3O2(SiO4)2(OH)4
grassy green 
mono
6.5
1.72-1.73
3.58-3.61
Chondrodite
Mg5(SiO4)2(F, OH)2
light yellow, brown
mono
6-6.5
1.60-1.63
3.1-3.2
Chromite
FeCr2O4
iron-black to brownish black
iso
5.5
2.16
4.6
Chrysoberyl
BeAl2O4
yellowish to green
ortho
8.5
1.75
3.65-3.8
Chrysocolla
(Cu, Al)2H2Si2O5 (OH)4*nH2O
light green to turquoise-blue
amor
2-4
4
2.0-2.4
Cinnabar
HgS
red to vermillion
hex
2-2.5
2.81
8.1
Clinozoisite
Ca2Al3OSi3O12(OH)
grayish-white, green
mono
6-6.5
1.67-1.72
3.25-3.37
Cobaltite
CoAsS
silver-white
iso
5.5-6
-
6.3
Colemanite
CaB3O4(OH)3*H2O
colorless, white
mono
4-4.5
1.59
2.42
Columbite
(Fe, Mn) Nb2O6
black
ortho
6
-
5.3-7.3
Copper
Cu
copper-red
iso
2.5-3
-
8.9
Cordierite
(Mg, Fe)2Al4Si5O18*nH2O
blue, gray, brown
ortho
7-7.5
1.53-1.57
2.60-2.66
Corundum
Al2O3
gray, blue, pink, brown
trig
9
1.77
4.0
Covellite
CuS
indigo-blue to black
hex
1.5-2
-
4.6
Cristobalite
SiO2
colorless, white
iso
7
1.48
2.32
Crocoite
PbCrO4
red
mono
2.5-3
2.36
5.9-6.1
Cryolite
Na3AlF6
colorless, white
mono
2.5
1.34
2.95-3.0
Cummingtonite
(Fe, Mg, Mn)7Si8O22(OH)2
brown
mono
6
1.66-1.68
3.2-3.6
Cuprite
Cu2O
red
iso
3.5-4
-
6.0
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