sulfides 9-12 SET 3

Question 1

Realgar formula

Answer 1

As4S4

Question 2

Realgar crystal form

Answer 2

• monoclinic, uncommon crystals
• coarse to fine grained earthy encrustations

Question 3

Realgar cleavage

Answer 3

pinacoidal good

Question 4

Realgar hardness

Answer 4

1.5 to 2 sectile

Question 5

Realga specific gravity

Answer 5

3.48

Question 6

Realgar color

Answer 6

resinous, transparent to translucent. red to orange and red to orange streak

Question 7

Realgar occurrence

Answer 7

• in hydrothermal veins with orpiment
• assoc with lead and silver minerals and well as stibnite
• as volcanic sublimation product
• deposit from hot springs

Question 8

Realgar remarks

Answer 8

red color, orange red streak, resinous luster and invariable assoc with orpiment

Question 9

orpiment formula

Answer 9

As2S3

Question 10

orpiment crystal form

Answer 10

• monoclinic, rare crystals
• usually foliated, columnar, or fibrous masses

Question 11

orpiment cleavage

Answer 11

pinacoidal perfect 010. flexible cleavage laminae, not elastic

Question 12

orpiment hardness

Answer 12

1.5 to 2 sectile

Question 13

orpiment specific gravity

Answer 13

3.49

Question 14

orpiment color

Answer 14

resinous translucent. lemon yellow, pale yellow streak

Question 15

orpiment occurrence

Answer 15

• rare mineral
• assoc with realgar, formed same conditions

Question 16

orpiment remarks

Answer 16

• yellow color
• foliated structure
• excellent cleavage

Question 17

how to differentiate orpiment and sulfur?

Answer 17

orpiment has perfect pinacoidal cleavage, sulfur has none, only conchoidal fracture.

also orpiment is sectile, sulfur is brittle

Question 18

stibnite formula

Answer 18

Sb2S3

Question 19

stibnite crystal form

Answer 19

• orthorhombic common crystals
• slender prismatic, with vertical striations in prism zone, the prisms appear bending or twisted bc of translation gliding
• often in radiating crystal groups or bladed forms with prominent cleavage
• massive coarse to fine granular

Question 20

stibnite cleavage

Answer 20

perfect pinacoidal 010, paralle striations 100

Question 21

stibnite hardness

Answer 21

2

Question 22

stibnite specific gravity

Answer 22

4.52 to 4.62

Question 23

stibnite color

Answer 23

metallic opaque. (very color on cleavage).
lead gray to black, same with streak

Question 24

stibnite occurrence

Answer 24

• in low temp hydrothermal veins or replacement deposits
• in hot spring deposits
• in assoc with other antimony minerals that formed as a product of its decomposition, with galena cinnabar, sphalerite, barite realgar orpiment and gold

Question 25

stibnite remarks

Answer 25

bladed habit, perfect one direction cleavage, lead gray color, soft black streak

Question 26

stibnite remarks

Answer 26

bladed habit, perfect one direction cleavage, lead gray color, soft black streak

Question 27

how to distinguish stibnite from galena

Answer 27

stibnite has a perfect pinacoidal cleavage, galena has perfect cubic.

it also is orthorhombic while galena is isometric

stibite also has lower specific gravity

Question 28

how to distinguish stibnite from galena

Answer 28

stibnite has a perfect pinacoidal cleavage, galena has perfect cubic.

it also is orthorhombic while galena is isometric

stibite also has lower specific gravity

Question 29

pyrite crystal form

Answer 29

• isometric, striated cube faces, pyritohedron, octahedron
• massive, granular, reniform, globular

Question 30

pyrite cleavage

Answer 30

none. conchoidal fracture, brittle

Question 31

pyrite hardness

Answer 31

6 to 6.5

Question 32

pyrite specific gravity

Answer 32

5.02

Question 33

pyrite color

Answer 33

pale brass yellow, darker because of tarnish. streak greenish to brownish black

Question 34

pyrite occurrence

Answer 34

• formed in high and low temperatures
• as magmatic segregation, accessory to igneous rocks, contact metamorphism and hydrothermal veins
• common in shales and limestone
• in vein deposits assoc with many mineral esp chalco, sphalerite and galena

Question 35

how to tell pyrite from gold

Answer 35

pyrite is paler in color, and also harder and brittle

Question 36

how to tell pyrite from marcasite

Answer 36

marcasite is even paler in color, marcasite is also orthorhombic while pyrite is isometric

Question 37

what mineral is easily altered from pyrite and what often results because of this?

Answer 37

limonite, often pseudomorphism results

Question 38

usually there is a capping of limonite in pyrite veins, what’s this called

Answer 38

gossan