Sulfides

Question 1

Chalcocite

Answer 1

Cu₂S

• putina (green colour from copper)
• dark lead-gray
• streak gray or black
• shiny
• can be cut with knife
• very brittle

Question 2

Covellite

Answer 2

CuS

• Indigo or dark blue
• cleaves into thin sheets (chalcocite has no cleavage)
• streak lead-gray to black
• tiny peacock flakes can be see in host rock

Question 3

Bornite

Answer 3

Cu₅FeS₄

• coppery or bronze with peacock tarnish
• no cleavage
• streak pale grey-black

Question 4

Chalcopyrite

Answer 4

CuFeS₂

• tetrahedral crystals
• deep brass of golden yellow with iridecent tarnish
• greenish-black streak

Question 5

Pyrrhotite

Answer 5

Fe_1−xS

• bronze with dark brown tarnish
• magnetic
• no cleavage

Question 6

Pyrite

Answer 6

FeS₂

• Pale-yellow to brass
• streak greenish black
• often in striated cubes; isometric
• Might appear granular like pyrrhotite, need to look with hand lens in order to distinguish

Question 7

Marcasite

Answer 7

FeS₂

• radiating lenses (coxcombs spears)
• pale brass-yellow to white with yellow or brown tarnish

Question 8

Pentlandite

Answer 8

(Fe,Ni)₉S₈

• _{<span>​usually in light, bronze-yellow masses</span>}
• _{<span>light bronze-brown streak</span>}
• _{<span>not out in lab</span>}

Question 9

Galena

Answer 9

PbS

• dark lead-gray cubes or octahedrons
• perfect cubic cleavage
• streak lead-gray
• very dense

Question 10

Sphalerite

Answer 10

ZnS

• resinous or adamantine crystals
• perfect dodecahedral cleavage

Question 11

Cinnabar

Answer 11

HgS

• Bright red to brownish
• usually granular
• heavy
• scarlet streak

Question 12

Realgar

Answer 12

AsS

• usually earthy
• deep red or orange colour
• streak orange-yellow
• in the photo realgar is red

Question 13

Orpiment

Answer 13

As₂S₃

• lemon-yellow
• streak lemon-yellow
• cleaves into thin flexible flakes with peraly luster

Question 14

Stibnite

Answer 14

Sb₂S₃

• lead-gray with black tarnish
• will make dark lead-gray streak on paper

Question 15

Molybdenite

Answer 15

MoS₂

• blushish-lead gray
• greenish-black streak on paper
• cleaves into flexible sheets
• mild greasy feeling

Question 16

Arsenopyrite

Answer 16

FeAsS

• silver-white to steel gray
• streak grayish black
• usually massive or in prismatic crystals (small)
• heavy