Mineral Names underlined are subject for lab examination--site I.D.
Other material is subject for lecture
exam # 4
Minerals & info listed under I = (lab exam 3 and lecture exam #4)
Minerals " " listed under II = (lab exam 4 and
lecture exam #4)
I. Native Elements, Sulfides,
Sulfosalts, Oxides-Hydroxides and Halides (Chapters
15 and 16) (subject for lab exam 3 and
lecture exam 4)
A. Native Elements
-consist of minerals
comprised of atoms of only one element-there are 3 subclasses in this class
1. Metals
-Au, Ag, Cu,
Pt and Fe which are minerals possessing special properties including high
heat
and electrical conductance, malleability, ductility and a metallic bond
2. Semi-metals
-Sb and Bi are
minerals which are poorer in conductors of heat and electricity and are
more
brittle than the metals, and have a bond type intermediate between metallic
and
covalent
3. Non-metals
-graphite
(C) and sulfur (S) are nonconductors of electricity, very brittle and soft--minerals
have
a covalent bond--graphite is used as a source for carbon in the production
of steel
and S used in the production of sulfuric acid
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B. Sulfides
(including
arsenides and sulfarsenides)
-consist of minerals, predominantly
metallic in character, with the general formula AmXp,
in which X represents S or
to a lesser extent As, Sb, Bi, and Te and A represents one or
more metals--in the arsenides and
sulfarsenides, semimetals take the place of sulfur totally
(NiAs) or in part (FeAsS)
while in the sulfides, S is the only major anion
-consist of minerals known as "primary
ore minerals" formed directly from an aqueous
medium (hydrothermal
solutions) with no oxidation processes-
-chalcocite (Cu2S)--can
resemble enargite but does not have cleavage
-bornite (Cu5FeS4)--peacock
ore--displays a tarnish quality and may resemble covellite
but does not display prominent cleavage
-galena (PbS)--very high specific
gravity and displays prominent cubic cleavage--only
source for lead
-sphalerite (ZnS)--actually (Fe,Zn)S--is
usually resinous to adamantine with prominent
cleavage--yellowish to deep red (ruby ore) to black ("jack") indicating
a progressively higher content of Fe substituting for Zn--a geothermal
mineral--most important ore of zinc and important source of Cd--
leaves a rotten egg smell when scratched on a porcelain plate
-chalcopyrite (CuFeS2)--looks
like pyrite but no cleavage and softer than glass--can
resemble millerite but does not contain the radiating crystal habit-
resembles pyrrhotite and marcasite but chalcopyrite is not
magnetic and does not have the cockscomb structure res-
pectively
-pyrrhotite (Fe1-xS)--magnetic--Fe
deficiency with respect to sulfur ( where x = 0 to 0.2)
This deficiency forms an omission solid solution
and a defect structure
-nickeline
(niccolite) (NiAs)
-millerite (NiS)--hairlike radiating crystals
-pentlandite (Fe,Ni)9S8--closely
resembles pyrrhotite but not magnetic--the principal ore
of Ni
-covellite (CuS)--excellent
cleavage--often iridescent--can resemble bornite but has cleav-
age resembling mica-- often shows an indigo color
-cinnabar (HgS)--red and very dense with
prominent cleavage--most important ore of Hg
-realgar (AsS)--red and associated with
orpiment
-orpiment (As2S3)--yellow
and distinguished from sulfur by its prominent cleavage
-pyrite (FeS2)--most common
sulfide mineral--differs from chalcopyrite in that it scratches
glass--cube form with striations a common occurrence
-marcasite (FeS2)--a
polymorph of pyrite--differs from pyrite by its "cockscomb"
structure
-molybdenite (MoS2)--prominent
cleavage--distinguished from graphite by its higher
specific gravity and a bluish tone to the color--principle ore of Mo
-arsenopyrite (FeAsS)--distinguished
from marcasite by its silver-white color--principal
source of As
C. Sulfosalts
-these have the general formula AmBnXp
which may be written as a double sulfide,
AmXq.BnX(p-q)
where A can be Ag, Cu, Pb and B can be As, Sb, Bi and X is S--the
semimetals act as cations in sulfosalts
as compared to anions in the sulfarsenides and
aresenides
-enargite (Cu3AsS4)--distinguished
from chalcocite by its prominent cleavage
D. Oxides-Hydroxides
OXIDES
-the bond type of the oxide minerals is
primarily ionic compared to the more prevalent
covalent bond in the sulfides and
sulfosalts--this results in part to a greater hardness
of the oxides compared to the sulfides
and sulfosalts
-cuprite
(Cu2O)--red
in various shades
-zincite
(ZnO)--occurs with black franklinite
1. Hematite group
-isostructural
group in which there are 6 O surrounding each respective
cation and 4
respective cations surrounding each O (ev of bonds =1/2)
-corundum
(Al2O3)--very hard--hardness of 9 on Moh's hardness
scale--sapphires
(blue) and
rubies (red) are important gemstone varieties
-hematite (Fe2O3)--most
important ore of Fe--may be oolitic hematite (non metallic),
specularite or
massive
hematite (metallic luster)
-ilmenite
(FeTiO3)--distinguished from magnetite by its lack of strong
magnetism--the
major source of Ti
2. Rutile group
-isostructural
group in which 6 O surround each cation and 3 respective
cations surround
each O
-rutile
(TiO2)--reddish color--distinguished from cassiterite by
its
much lower specific gravity
-pyrolusite
(MnO2)--low hardness--leaves a black streak on paper--the most
important Mn ore
-cassiterite
(SnO2)--very high specific gravity--principle ore of Sn
3. Spinel group
-isostructural group
in which the first metal
in formula is +2 and second mineral +3
-magnetite (Fe3O4) or (FeO).(Fe2O3)
or (FeFe2O4)--magnetic
-chromite
(FeCr2O4)--massive to granular--the only ore of Cr
-franklinite
(Zn, Fe, Mn) (Fe, Mn)2O4--distinguished from magnetite by its lack
of
strong magnetism and association with zincite
HYDROXIDES
-brucite
(Mg(OH)2)--distinguished from talc by a
greater hardness and lack of greasy
feel
-manganite
(MnO(OH))--distinguished from pyrolusite by its brown
streak--often
occurs in prismatic crystals
-romanechite
(psilomelane) (Ba(Mn+2)(Mn+4)8O16 (OH)4)--often
occurs in botryoidal
form
-goethite
(FeO(OH))
-bauxite (mixture of minerals)--most important ore of Al--recognized by its
pisolitic
character
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OXIDES AND HYDROXIDES
E. Halides
-consist of minerals with a halogen anion
-halite (NaCl)--distinguished by its cubic cleavage and salty
taste--less bitter
taste
than that for sylvite (KCl)
-cryolite (Na3AlF6)
-fluorite (CaF2)--often found in cubes and has an octahedral
cleavage--is an important
source for F in the production of HF
II. Carbonates, Borates, Sulfates,
Tungstates, Molybdates, Vanadates,
Phosphates (Chapter 17) (subject for
lab exam 4 and lecture exam 4)
-as mentioned in the section "Atomic Structure
of Minerals" the anisodesmic bond
is prominent in the minerals of these
classes--the B-O bond in the borate mineral class
is mesodesmic--go
back and review the different bond types
A. Carbonates
1. Calcite group
-isostructural group with 6 oxygens
surrounding each Ca or Mg or Fe, or Mn, or Zn
atom 3 O surrounding each C, and 1 C and 2 of the respective
aforementioned
cations surrounding each O
-calcite
(CaCO3)--prominent rhombohedral cleavage and often found as rhombohedron
and/or scalenohedron crystals--distinguished from other minerals
by the strong effervescence with cold HCl in a solid-non powdered
form
-magnesite
(MgCO3)--prominent rhombohedral cleavage but rare and usually fine to
cryptocrystalline and white
-siderite
(FeCO3)--prominent rhombohedral cleavage with curved faces--distinguished
from other carbonates by its light to dark color and from
sphalerite by its rhombohedral cleavage and lack of sulfur smell of
the powder on a streak plate
-rhodochrosite
( MnCO3)--prominent rhombohedral cleavage with curved faces
and
distinguished by its pink color
-smithsonite
(ZnCO3)--prominent cleavage--usually blue-green in color and botryoidal
or stalactitic in its form
2. Aragonite
group
-isostructural group
with 9 oxygens
surrounding each cation other than C, 3 O sur-
rounding each C, and 1 C and 3 respective cations surrounding
each O
-aragonite
(CaCO3)--polymorphic with calcite--distinguished from calcite by its lack
of rhombohedral cleavage and from witherite and strontianite by
its lower specific gravity
-witherite
(BaCO3)--very dense--distinguished from barite by its effervescence in cold
HCl in powdered form
3. Dolomite group
-isostructural group similar to that of the
calcite group
-dolomite (CaMg(CO3)2)--crystal
varieties abundantly show curved rhombohedral
crystals--effervesces in hot HCl or in dilute HCl in powder
form only
4. Hydrous carbonate group
-malachite (Cu2CO3(OH)2)--distinguished
by its bright green color and botryoidal forms,
effervesces slightly with cold HCl yielding a green solution
-azurite (Cu3(CO3)2(OH)2)--characterized
by its azure-blue color and effervescence in HCl
B. Borates
-because of the presence of a mesodesmic bond
between B and O, there is polymerization
between basic units as in the
silicates---borates are the most important source of B and
borax
-kernite (hydrated Na Borate)--characterized by its
long splintery cleavage fragments and
slow solubility in cold water--can resemble gypsum but is harder
-borax ("
" "
)--characterized by its crystals and easy solubility in cold water
-colemanite("
Ca "
)--commonly found in short prismatic crystals
C. Sulfates
1. Barite group
-isostructural
group in which 12 O surround each Ba or Sr or Pb, 4 O
surround each S,
and 1 S and 3 of the respective aforementioned cations surround each
O
-barite (BaSO4)--distinguished by its prominent cleavage, very high specific
gravity,
and crystals--is the chief source of Ba--can occur in several forms
as bladed barite, clear barite, black barite, and rose barite
-anhydrite (CaSO4)--is
not isostructural with the barite group because of the 8 O surround-
ing each Ca with 1 S and only 2 Ca surrounding each O--3 right
angle directions of cleavage
2. Hydrous sulfate
group
-gypsum (CaSO4.2H2O)--characterized
by its softness and 3 unequal cleavages--there are
various varieties as bladed gypsum, selenite (clear) gypsum,
satin spar gypsum, and massive or alabaster gypsum
-alunite (KAl3(SO4)2(OH)6)
D. Tungstates,
Molybdates and Vanadates
1. Tungstates
-wolframite
group is an isostructural group
with abundant solid solution between FeWO4,
ferberite
and MnWO4, heubnerite
-wolframite ((Fe,Mn)WO4)--distinguished
from other minerals by its black color, one
directional cleavage, and high specific gravity--chief source
of W
2. Molybdates
-wulfenite (PbMoO4)--characterized
by its tabular (tetragonal) crystals and its orange to
yellow color and high specific gravity
3. Vanadates
-vanadinite ((Pb5(VO4)3Cl)--characterized
by its ruby-red, to orange-red color, resinous
luster and high specific gravity
E. Phosphates
-monazite ((Ce,La,Y,Th)PO4)--a
rare earth phosphate--very high specific gravity mineral--
the main source of Th and some other rare earth elements
-apatite (Ca5(PO4)3(F,Cl,OH))--green
apatite, yellow and red apatite are some colors
in which this mineral occurs
-amblygonite (LiAlFPO4)--distinguished
from plagioclase by the lack of striation twinning
-wavellite (Al3(PO4)2(OH)3.5H2O)--almost
always found in radiating crystal form and
usually green in color
-turquoise (Cu
phosphate)--distinguished by its color and harder than chrysocolla
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SULFATES, PHOSPHATES AND CAR-
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