HYDROXIDES

Question 1

Mg(OH)2

Answer 1

Brucite

Question 2

Commonly foliated, massive. When in crystals, they are hexagonal, usually tabular on {0001}

Answer 2

crystal form of brucite

Question 3

What is the cleavage of brucite?

Answer 3

Basal {0001} perfect. Folia flexible but not elastic. Sectile.

Question 4

What is the hardness of brucite?

Answer 4

2 1/2

Question 5

What is the specific gravity of brucite?

Answer 5

2.39

Question 6

What is the usual color of brucite?

Answer 6

White, gray, light green. Luster on base pearly, elsewhere vitreous to waxy.

Question 7

Found in association with serpentine dolomite, magnetite, and chromite. As a reaction product of Mg-silicates, especially serpentine.

Answer 7

Brucite

Question 8

MnO(OH)

Answer 8

Manganite

Question 9

Monoclinic crystals that are prismatic parallel to the c axis and vertically striated. Often columnar to coarse – fibrous.

Answer 9

crystal form of manganite

Question 10

What is the cleavage of manganite?

Answer 10

Pinacoidal {010} perfect, {110} and {001} good

Question 11

What is the hardness of manganite?

Answer 11

4

Question 12

What is the specific gravity of manganite?

Answer 12

4.3

Question 13

What is the usual color of manganite

Answer 13

Steel gray to iron black.

Question 14

In manganese deposits associated with other Mn-oxides and hydroxides. Also in low-temperature hydrothermal veins associated with barite, siderite, and calcite. It commonly alters to pyrolusite.

Answer 14

Manganite

Question 15

(Ba,H2O)2(Mn4+,Mn3+)5O10

Answer 15

Romanechite

Question 16

Massive, botryoidal, stalactitic; appears amorphous.

Answer 16

Romanechite

Question 17

What is the hardness of romanechite?

Answer 17

5-6

Question 18

What is the specific gravity of romanechite?

Answer 18

3.7-4.7

Question 19

What is the usual color of romanechite?

Answer 19

Black. Opaque. Luster submetallic. Streak brownish black.

Question 20

A product of secondary alteration of original Mn-carbonates, Mn-silicates, or both. Generally in association with pyrolusite in manganese ore deposits, in nodular deposits in bogs, and on lake bottoms and on see and ocean floors.

Answer 20

Romanechite

Question 21

Mixtures of manganese oxides of which romanechite is a major constituent.

Answer 21

psilomelane

Question 22

FeO(OH)

Answer 22

Goethite

Question 23

Rarely in distinct prismatic (orthorhombic), vertically striated crystals. Generally massive, reniform, stalactitic, and in radiating fibrous aggregation.

Answer 23

crystal form of geothite

Question 24

Goethite is also called ________ generally loose and porous.

Answer 24

bog ore

Question 25

What is the cleavage of goethite?

Answer 25

Pinacoidal {010} perfect

Question 26

What is the hardness of goethite?

Answer 26

5 - 5 1/2

Question 27

What is the specific gravity of goethite?

Answer 27

4.37, but may be as low as 3.3 for impure material

Question 28

What is the usual color of goethite?

Answer 28

Yellowish brown to dark brown. Luster adamantine to dull, silky in some fine, scaly, or fibrous varieties.

Question 29

A common mineral resulting from oxidation and weathering of iron-bearing minerals. It is a widespread deposit in bogs and around springs

Answer 29

Goethite

Question 30

Goethite constitutes the gossan or “________" over metalliferous vein deposits.

Answer 30

iron hat

Question 31

FeO(OH)·nH2O

Answer 31

Limonite

Question 32

___________ field term used for very fine-grained to amorphous mixtures of brown ferric hydroxides whose real identities are unknown

Answer 32

limonite

Question 33

Limonite, therefore, has variable compositions (and variable chemical and physical properties) and consists of a mixture of several iron hydroxides (commonly with _________ a major constituent)

Answer 33

goethite

Question 34

Al2O3. 2H2O

Answer 34

Bauxite

Question 35

Bauxite consists of a very fine-grained intergrowth of three aluminum hydroxides, ______, _________, and _______

Answer 35

diaspore, gibbsite, boehmite

Question 36

A mixture. Pisolitic, in round concretionary grains. Also massive, earthy, claylike.

Answer 36

Bauxite

Question 37

What is the hardness of bauxite?

Answer 37

1-3

Question 38

What is the specific gravity of bauxite?

Answer 38

2-2.55

Question 39

What is the color of bauxite?

Answer 39

White, gray, yellow, red. Yellow color caused by limonite staining.

Question 40

__________ is of supergene origin, commonly produced under subtropical to tropical conditions by prolonged weathering and leaching of silica from aluminum-bearing rocks

Answer 40

bauxite