oxides part 2

Question 1

rutile formula

Answer 1

TiO2

Question 2

rutile crystal form

Answer 2

• tetragonal, prismatic with dipyramid terminations and vertically striated prism faces
• in elbow twins
• slender and acicular habit
• compact massive

Question 3

rutile cleavage

Answer 3

distinct prismatic

Question 4

rutile hardness

Answer 4

6 to 6.5

Question 5

rutile specific gravity

Answer 5

4.18 to 4.25

Question 6

rutile color

Answer 6

• adamantine to submetallic
• red, reddish brown to black
• pale brown streak

Question 7

rutile occurrence

Answer 7

• in granite and granite pegmatites, mica schist, gneiss
• in metamorphic limestone and dolomite
• may be in quartz and micas as fine slender crystals

Question 8

rutile remarks

Answer 8

red color and adamatine

Question 9

how to tell rutile from cassiterite

Answer 9

rutile has lower specific gravity

Question 10

pyrolusite formula

Answer 10

MnO2

Question 11

pyrolusite crystal form

Answer 11

• radiating fibers or columns
• granular massive in reniform coats and dendritic shapes
• finely overgrown with other Mn oxides and hydroxides
• psuedomorphs after manganite

Question 12

pyrolusite cleavage

Answer 12

perfect prismatic, splintery fracture

Question 13

pyrolusite hardness

Answer 13

1-2

Question 14

the coarse crystalline variety of pyrolusite

Answer 14

polianite

Question 15

hardness of polianite

Answer 15

6 to 6.5

Question 16

pyrolusite specific gravity

Answer 16

4.75

Question 17

pyrolusite color

Answer 17

• iron black, same streak
• metallic opaque

Question 18

pyrolusite occurrence

Answer 18

• most common manganese ore mineral, widespread
• in nodular deposits in bogs, on lake bottoms and ocean floors
• in veins assoc with quartz and various metallic minerals

Question 19

pyrolusite remarks

Answer 19

black color and streak, low degree of hardness

Question 20

cassiterite formula

Answer 20

SnO2

Question 21

cassiterite crystal form

Answer 21

• if crystals: 2 tetragonal prisms and dipyramids
• in elbow shaped twins
• usually massive granular
• also reniform with radiating fibrous appearance

Question 22

what do you call the reniform radiating fibrous variety of cassiterite

Answer 22

wood tin

Question 23

cassiterite cleavage

Answer 23

imperfect prismatic

Question 24

cassiterite hardness

Answer 24

6.7

Question 25

cassiterite specific gravity

Answer 25

6.8 to 7.1

Question 26

cassiterite color

Answer 26

• usually brown or black
• rare yellow or white
• white streak
• adamantine, submetallic, dull, transparent translucent

Question 27

cassiterite occurrence

Answer 27

• as accessory mineral of igneous rocks and pegmatites
• commonly in high temp hydrothermal veins or gear granitic rocks
• veins assoc include tourmaline, topaz, fluorite…
• as rolled pebbles in placer deposits

Question 28

what do you call cassiterite that occurs as rolled pebbles in places deposits

Answer 28

stream tin

Question 29

cassiterite remarks

Answer 29

high specific gravity, adamantine luster, light streak

Question 30

uraninite formula

Answer 30

UO2

Question 31

uraninite crystal form

Answer 31

• most commonly botryoidal or massive, with banded structure

Question 32

what do you call the variety of uraninite with banded structure

Answer 32

pitchblende

Question 33

uraninite hardness

Answer 33

5.5

Question 34

uraninite specific gravity

Answer 34

6.5 to 9 pitchblende
7.5 to 9.7 for crystals

Question 35

uraninite color

Answer 35

• submetallic to pitchlike dull
• black
• brownish black streak

Question 36

uraninite occurrence

Answer 36

• primary constituent of granitic rocks and pegmatites
• in high temp hydrothermal veins assoc with cassiterite, chalco, arsenooy
• in low temp assoc with secondary uranium minerals

Question 37

uraninite remarks

Answer 37

• mainly by pitchy luster, high specific gravity, color streak, and strong radioactivity

Question 38

how to detect radioactivity in uraninite

Answer 38

by Geiger counter or scintillation counter