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DAY 2: FINAL EXAM > SULFIDES > Flashcards

SULFIDES Flashcards

1
Q

CuS2

A

Chalcocite

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2
Q

Most commonly massive and very fine-grained. If in orthorhombic crystals, usually small and tabular with hexagonal outline.

A

Crystal form of Chalcocite

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3
Q

What is the cleavage of chalcocite

A

Prismatic {110} poor. Fracture conchoidal

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4
Q

What is the hardness of chalcocite?

A

2.5 - 3. Imperfectly sectile

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5
Q

What is the specific gravity of chalcocite?

A

5.5 - 5.8

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6
Q

It occurs as a primary mineral in hydrothermal veins, with bornite, chalcopyrite, enargite, and pyrite.

A

Chalcocite

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7
Q

Its most common occurrence is as a supergene mineral in enriched zones of sulfide deposits, often forming “_______” at the level of the water table.

A

chalcocite blankets

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8
Q

Cu5FeS4

A

Bornite

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9
Q

Rarely in tetragonal crystals; usually massive.

A

Crystal form of bornite

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10
Q

Hardness of bornite

A

3

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11
Q

What is the color of chalcocite?

A

Shining lead gray, tarnished to dull black upon exposure.

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12
Q

What is the specific gravity of bornite?

A

5.06-5.08

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13
Q

What is the color of bornite?

A

Brownish bronze on fresh surface but quickly tarnished to variegated purple and blue (hence
called peacock ore) and finally to almost black on exposure.

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14
Q

Commonly associated with other sulfides such as chalcocite, chalcopyrite, covellite, pyrrhotite,
and pyrite in hypogene deposits. It occurs less frequently as a supergene mineral in the upper
enriched parts of copper veins.

A

Bornite

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15
Q

PbS

A

Galena

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16
Q

Isometric crystals with the most common form the cube, sometimes truncated by the octahedron. Commonly in coarse- to fine-grained cleavable and granular masses.

A

crystal form of galena

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17
Q

What is the cleavage of galena?

A

Cubic {001} perfect

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18
Q

What is the hardness of galena?

A

2.5

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19
Q

What is the specific gravity of galena?

A

7.4 - 7.6

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20
Q

What is the color of galena?

A

Lead-gray with lead-gray streak.

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21
Q

Common metallic sulfide, found in veins associated with sphalerite, marcasite,
chalcopyrite, cerussite, anglesite, calcite, quartz, barite, and fluorite.

A

Galena

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22
Q

ZnS

A

Sphalerite

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23
Q

Isometric with the tetrahedron, dodecahedron, and cube as common forms. Crystals are frequently highly complex and usually malformed or in rounded aggregates.

A

sphalerite crystal form

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24
Q

What is the cleavage of sphalerite?

A

Dodecahedral {011} perfect but some sphalerite is too fine-grained to show cleavage.

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25
What is the hardness of sphalerite?
3.5 - 4
26
What is the specific gravity of sphalerite?
3.9 - 4.1
27
What is the color of sphalerite?
Colorless when pure ZnS and green when nearly so. Commonly yellow, brown to black, darkening with increase in iron. Also red (ruby zinc).
28
The most common ore mineral of zinc, is widely distributed. Its occurrence and mode of origin are similar to those of galena, with which it is commonly associated.
Sphalerite
29
CuFeS2
Chalcopyrite
30
Tetragonal, commonly appearing tetrahedral on account of the disphenoid {112}. Usually massive.
crystal form of chalcopyrite
31
What is the hardness of chalcopyrite?
3.5 - 4; brittle
32
What is the specific gravity of chalcopyrite?
3.1 - 3.4
33
What is the color of chalcopyrite?
Brass yellow; often tarnished to bronze or irridescent.
34
Very common in occurrence and is one of the most important ore minerals of copper. In low-temperature hydrothermal vein deposits it is found with galena, sphalerite, and dolomite. In higher-temperature deposits it may occur with pyrrhotite and pentlandite.
Chalcopyrite
35
Also known as fools gold.
Chalcopyrite
36
(Fe(1-x)S) x = 0 - 0.2
Pyrrhotite
37
Hexagonal (for the high-temperature form),but crystals uncommon. Usually massive,granular.
crystal form of pyrrhotite
38
What is the hardness of pyrrhotite?
4
39
What is the specific gravity of pyrrhotite?
4.58-4.65
40
Intensity may be variable. Generally easily attracted to a magnet, but much less magnetic than magnetite.
Magnetism of pyrrhotite
41
What is the color of pyrrhotite?
Brownish bronze.
42
Occurs as disseminated grains in basic igneous rocks such as norites. In sulfide ore deposits commonly associated with pentlandite, chalcopyrite, and other sulfides.
pyrrhotite
43
(Fe,Ni)9S8
Pentlandite
44
Isometric, but most commonly massive, in granular aggregates with octahedral parting.
Pentlandite
45
What is the hardness of pentlandite?
3.5-4
46
What is the specific gravity of pentlandite?
4.6 - 5.0
47
What is the color of pentlandite?
Yellowish bronze
48
The major ore mineral for nickel, found in basic igneous rocks associated with nickel sulfides, and chalcopyrite; probably formed by processes of magmatic segregation.
Pentlandite
49
CuS
Covellite
50
Rarely in tabular, hexagonal crystals. Usually massive as coatings or disseminations through other copper minerals.
crystal form of covellite
51
What is the cleavage of covellite?
Basal {0001} perfect
52
What is the hardness of covellite?
1.5 - 2
53
What is the specific gravity of covellite?
4.6 - 4.76
54
What is the color of covellite?
Indigo blue or darker.
55
It is not an abundant mineral but is commonly found in most copper ore deposits as a supergene mineral. It is found with other copper minerals, mainly chalcocite, chalcopyrite, bornite, and enargite, and derived from them by alteration.
Covellite
56
As4S4
Realgar
57
Monoclinic, but crystals uncommon. Generally coarse- to fine-granular and often earthy and as encrustations.
crystal form of realgar
58
What is the cleavage of realgar?
Pinacoidal good
59
What is the hardness of realgar?
1.5 - 2;sectile
60
What is the specific gravity of realgar?
3.48
61
What is the color of realgar?
Red to orange. Streak also red to orange.
62
Found in hydrothermal veins with orpiment, associated with lead and silver minerals, as well as with stibnite. It also occurs as a volcanic sublimation product and as a deposit from hot springs.
occurrence of realgar
63
As2S3
Orpiment
64
Monoclinic, but crystals rare. Usually in foliated, columnar, or fibrous masses
crystal form of orpiment
65
What is the cleavage of orpiment?
Pinacoidal {010} perfect.
66
What is the hardness of orpiment?
1.5 - 2
67
What is the specific gravity of orpiment?
3.49
68
What is the color of orpiment?
Lemon yellow. Streak pale yellow.
69
A rare mineral, associated usually with realgar and formed under similar conditions.
Orpiment
70
Orthorhombic. Crystals common. Slender prismatic habit with the prism zone vertically striated. Most prisms appear bent or twisted as a result of translation gliding.
Stibnite crystal form
71
Sb2S3
stibnite
72
What is the cleavage of stibnite?
Pinacoidal {010} perfect, with striations parallel to [100]
73
What is the hardness of stibnite?
2
74
What is the specific gravity of stibnite?
4.52-4.62
75
What is the color of stibnite?
Lead-gray to black. Streak also lead-gray to black.
76
Found in low-temperature hydrothermal veins or replacement deposits and in hotsprings deposits. It is associated with other antimony minerals that have formed as the product of its decomposition, and with galena, cinnabar, sphalerite, barite, realgar, orpiment, and gold.
Stibnite
77
FeS2
Pyrite
78
Isometric. Frequently in crystals. The most common forms are the cube (the faces of which are usually striated), the pyritohedron, and the octahedron.
crystal form of pyrite
79
What is the cleavage of pyrite?
None. Fracture conchoidal.
80
What is the hardness of pyrite?
6-6.5
81
What is the color of pyrite?
Pale brass yellow; may be darker because of tarnish.
82
One of the most common and widespread sulfide minerals, it is formed at both high and low temperatures. It occurs as magmatic segregations, as an accessory mineral in igneous rocks, and in contact metamorphic deposits and hydrothermal veins.
Pyrite
83
Pyrite veins are usually capped by a cellular deposit of limonite, termed ___________.
gossan
84
FeS2
Marcasite
85
Orthorhombic. Polymorphous with pyrite. Crystals commonly tabular on {010}; less commonly prismatic parallel to [001]. Often twinned, giving cockscomb and spear-headed groups.
crystal form of marcasite
86
What is the hardness of marcasite?
6-6.5
87
What is the specific gravity of marcasite
4.89
88
What is the color of marcasite?
Pale bronze-yellow to almost white on fresh fracture. Yellow to brown tarnish.
89
It is found in metalliferous veins, frequently with lead and zinc ores. It is less stable than pyrite (being easily decomposed) and much less common. It is commonly found as a supergene mineral deposited at low temperatures, at near-surface conditions.
Marcasite
90
MoS2
Molybdenite
91
Hexagonal. Crystals in hexagonal plates or short, slightly tapering prisms. Commonly foliated, massive, or in scales.
crystal form of molybdenite
92
What is the cleavage of molybdenite?
Basal {0001} perfect, with laminae flexible but not elastic.
93
What is the hardness of molybdenite?
1-1.5; greasy feel
94
What is the specific gravity of molybdenite?
4.62-4.73
95
What is the color of molybdenite?
Lead-gray. Streak grayish black.
96
Found as an accessory mineral in some granites; in pegmatites and aplites. Common in high-temperature vein deposits associated with cassiterite, scheelite, and fluorite.
Molybdenite
97
FeAsS
Arsenopyrite
98
Monoclinic. Crystals are commonly prismatic and elongated along the c axis and less commonly along the b. Sometimes with faces striated parallel to [101].
crystal form of FeAsS
99
What is the cleavage of arsenopyrite?
Prismatic {101}
100
What is the hardness of arsenopyrite?
5.5 - 6
101
What is the specific gravity of arsenopyrite?
6.07
102
What is the color of arsenopyrite?
Silver-white. Streak black.
103
It is the most common mineral containing arsenic. It occurs with tin and tungsten ores in high-temperature hydrothermal deposits.
Arsenopyrite
104
Cu3AsS4
Enargite
105
Orthorhombic. Crystals elongated parallel to the c axis and vertically striated. Also tabular parallel to {001}. Columnar, bladed, massive.
crystal form of enargite
106
What is the cleavage of enargite?
Prismatic {110} perfect
107
What is the hardness of enargite?
3
108
What is the specific gravity of enargite?
4.45
109
What is the color of enargite?
Grayish black to iron-black. Streak also grayish black to iron-black.
110
Found in vein and replacement deposits formed at moderate temperatures associated with pyrite, sphalerite, bornite, galena, and chalcocite
Enargite

DAY 2: FINAL EXAM (13 decks)

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