03Classification

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5 Φεβ 2013 (πριν από 4 χρόνια και 6 μήνες)

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Classification of Minerals by
Anionic Species

(Anions are negative ions)


Anions are Negative Ions


May be single species


O
2
-
, F
-
, Cl
-
, S
2
-


May be anionic group
(
polyanion
):


CO
3
2
-
, SO
4
2
-
, PO
4
3
-


Silicates are classified by
polymerization.


Isolated tetrahedra


Chains


Sheets


Frameworks

Periodic Table

Native Elements

(no anions)


Pure elements that occur as
minerals


Graphite
,
diamond

(C)


Sulfur

(S)


Gold

(Au),
Silver

(Ag),
Copper

(Cu)


Iron

(kamacite)


Nickel

(taenite)


As, Te, Se, Pt, Ir, Os, Pd, Ru, Rh

Native Elements

Halides:

anion is F, Cl, Br or I


Halogens

are the elements F, Cl, Br, I


Halogens

are
monovalent

anions


Halite

(NaCl),
Sylvite

(KCl)


Fluorite

(CaF
2
)


Cryolite

Na
3
AlF
6

Sulfides: anion is S


Sulfur is “anion”, but mostly it is covalent


Pyrite
,
marcasite

(FeS
2
),
Chalcopyrite

(CuFeS
2
)


Sphalerite

ZnS,
Galena

(PbS)


Chalcocite

Cu
2
S,
Covellite

(CuS),
Bornite

(Cu
5
FeS
4
)


Realgar

(AsS),
Orpiment

(As
2
S
3
),
Cinnabar

(HgS)


Stibnite

(Sb
2
S
3
),
Molybdenite

(MoS
2
)


Sulfide minerals typically have
metallic luster, covalent bonding,
and occur in
hydrothermal

veins.


Only rarely do they occur at the
surface.

Elements in Sulfide Minerals

Oxides (Single):

anion is O (no polyanion)


Hemi
-
oxide
Cuprite

(Cu
2
O), Ice (H
2
O)


Monoxides


Periclase

group MgO, FeO, CaO, MnO


Zincite

ZnO,
Bromellite

BeO


Sesquioxides


Corundum

Al
2
O
3
,
Hematite

Fe
2
O
3


Dioxides


Rutile

TiO
2
,
Cassiterite

SnO
2
,
Pyrolusite

MnO
2

Oxides (Complex):

anion is O


Ilmenite

FeTiO
3


Spinel

Group


Spinel MgAl
2
O
4
, Magnetite Fe
3
O
4


Perovskite

CaTiO
3

Hydroxides:

anion is OH

Hydroxides:

anion is OH


Brucite

Mg(OH)
2


Gibbsite

Al(OH)
3


Diaspore

AlOOH(Bauxite)


Goethite

FeOOH

Carbonates

anion is (CO
3
)
2
-

Carbonates

anion is (CO
3
)
2
-


Calcite

CaCO
3
,
Rhodochrosite

MnCO
3


Aragonite

CaCO
3
,
Witherite

BaCO
3


Dolomite

CaMg(CO
3
)
2


Malachite

and
Azurite

Sulfates and Phosphates:

(SO
4
)
2
-

and (PO
4
)
3
-

Sulfates and Phosphates:

(SO
4
)
2
-

and (PO
4
)
3
-


Barite

(BaSO
4
),
Celestine

(SrSO
4
)


Gypsum

CaSO
4
.
2H
2
O


Anhydrite

CaSO
4


Apatite

Ca
5
(PO
4
)
3
OH


Turquoise

CuAl
6
(PO
4
)
4
(OH)
8
∙4H
2
O

Silicates are classified
by polymerization


Orthosilicates

(SiO
4
)
4
-
: Isolated
tetrahedra


Sorosilicates

(Si
2
O
7
)
6
-

‘Bow
-
Ties’


Chain silicates


(SiO
3
)
2
-

: Infinite single chains


(Si
4
O
11
)
6
-

: Double Chains


Sheet Silicates

(Si
4
O
10
)
4
-

sheets


Framework Silicates

(SiO
2
)
framework

Orthosilicates: (SiO
4
)
4
-


Isolated SiO
4
tetrahedra


Olivine

Group (Mg
2
SiO
4
)


Garnet

Group (Mg
3
Al
2
Si
3
O
12
)


Aluminosilicate

Group (Al
2
SiO
5
)


Staurolite
,
Zircon
,
Titanite

Orthosilicates:

Isolated Tetrahedra

Sorosilicates and
Cyclosilicates


Epidote

Group Ca
2
Al
2
FeSi
3
O
12
(OH)


Tourmaline

NaMg
3
Al
5
B
3
Si
6
O
27
(OH)
4


Beryl

Be
3
Al
2
Si
6
O
18


Cordierite

(Mg,Fe)
2
Al(AlSi
5
)O
18

•nH
2
O


Chain Silicates


Single Chains


Orthopyroxenes

Mg
2
Si
2
O
6



Clinopyroxenes

CaMgSi
2
O
6



Pyroxenoids

Ca
3
Si
3
O
9


Double Chains


Amphiboles

(Mg,Fe)
7
Si
8
O
22
(OH)
2

Chain Silicates

Layer Silicates


Antigorite


Mg
3
Si
2
O
5
(OH)
4




Talc



Mg
3
Si
4
O
10
(OH)
2




Kaolinite


Al
2
Si
2
O
5
(OH)
4



Pyrophyllite

Al
2
Si
4
O
10
(OH)
2




Biotite


K(Mg,Fe)
3
AlSi
3
O
10
(OH)
2


Muscovite


KAl
2
AlSi
3
O
10
(OH)
2



Chlorite


(Mg,Fe)
6
AlSi
3
O
10
(OH)
2



Layer Silicates

Framework Silicates

(Tektosilicates)


Silica Group

SiO
2


Alkali Feldspar

(Na,K)AlSi
3
O
8


Plagioclase

NaAlSi
3
O
8
-
CaAl
2
Si
2
O
8


Feldspathoids

(Leucite, Kalsilite, etc)


Zeolites

(open hydrous frameworks)

Tektosilicates

(Framework Silicates)