oxides pt 1

Question 1

in general how do oxides occur?

Answer 1

• as accessory minerals in igneous and metamorphic rocks
• as detrital grains in sediments

Question 2

cuprite formula

Answer 2

Cu2O

Question 3

cuprite crystal form

Answer 3

• isometric: cube, octhedron, dodecahedron

Question 4

cuprite hardness

Answer 4

3.5 to 4

Question 5

cuprite specific gravity

Answer 5

6.1

Question 6

cuprite color

Answer 6

• metallic-adamantine
• various shades of red
• brownish red streak

Question 7

ruby red transparent crystal variety of cuprite

Answer 7

ruby copper

Question 8

cuprite occurrence

Answer 8

• supergene mineral in oxidized portions in copper deposits
• assoc with limonite, secondary copper minerals

Question 9

cuprite remarks

Answer 9

• red color, isometric, high luster, brown streak and assoc with limonite

Question 10

corundum formula

Answer 10

Al2O3

Question 11

corundum crystal form

Answer 11

• common prismatic/tabular hexagonal crystals
• hexagonal dipyramids, rounded in barrel shapes with deep horizontal striations
• usually rudely crystallized, massive fine or coarse

Question 12

corundum cleavage

Answer 12

none. parting on 0001 and 10 1 1

Question 13

corundum hardness

Answer 13

9, may alter to mica (dapat fresh)

Question 14

corundum specific gravity

Answer 14

4.02

Question 15

corundum color

Answer 15

• adamantine to vitreous transparent to translucent
• shades of brown pink blue
• any color or colorness

Question 16

what is red corundum

Answer 16

ruby

Question 17

what is gem corundum of any color

Answer 17

sapphire

Question 18

corundum occurrence

Answer 18

• common accessory in some metamorphic rocks: limestone, mica schist, gneiss
• in SiO2 poor igneous rocks: syenites and nepheline syenites
• as rolled pebbles in detrital soil and stream sands

Question 19

corundum remarks

Answer 19

great hardness, high luster, parting and specific gravity

Question 20

hematite formula

Answer 20

Fe2O3

Question 21

hematite crystal form

Answer 21

• crystals: usually thick to thin tabular on 0001 with hexagonal outline
• thin plates grouped in rosettes
• botryoidal to reniform in radiating structures
• may also be micaceous and foliated also earthy

Question 22

hematite is aka?

Answer 22

kidney ore

Question 23

term for the micaceous and foliated hematite

Answer 23

specular hematite

Question 24

hematite cleavage

Answer 24

parting on 10 1 and 0001

Question 25

hematite hardness

Answer 25

5.5 to 6.5 (crystals)

Question 26

hematite specific gravity

Answer 26

5.26 (crystals)

Question 27

hematite color

Answer 27

• reddish brown to black
• dull in earthy
• light to dark red streak

Question 28

platy and metallic variety of hematite

Answer 28

specularite

Question 29

red earthy variety of hematite

Answer 29

red ochre

Question 30

hematite occurrence

Answer 30

• accessory mineral in many rocks
• most abundant iron ore mineral in precambrian banded iron formations
• sublimation product in volcanic rocks
• accessory constituent in granite
• in metamorphic assemblages
• minor constituent of red sandstone, as cementing material binding quartz and grains together
• in oolitic sedimentary iron deposits

Question 31

ilmenite formula

Answer 31

FeTiO3

Question 32

ilmenite crystal form

Answer 32

• massive and compact
• in grains or as sand

Question 33

ilmenite hardness

Answer 33

5.5 to 6

Question 34

ilmenite specific gravity

Answer 34

4.7

Question 35

ilmenite color

Answer 35

• metallic to submetallic opaque
• iron black with metallic to submetallic luster
• brownish red streak

Question 36

ilmenite occurrence

Answer 36

• common accessory in igneous rocks
• large masses in gabbro, diorites and anorthosites
• commonly assoc with magnetite
• as constituent of black sand, assoc with magnetite, rutile and zircon

Question 37

how to distinguish ilmenite from hematite

Answer 37

hema has light to dark red streak, ilmenite has black to brownish red streak

Question 38

how to distinguish ilmenite from magnetite

Answer 38

hema is not strongly magnetic