Week 2

Question 1

Mineral

Answer 1

A naturally occurring, inorganic, solid element or compound with definite chemical composition and a regular internal crystal structure. Minerals are usually naturally occurring.

Minerals can be made of one type of element (diamond or carbon), metals (gold, silver, or copper), or compounds of several different elements (clays of Al, Si and other elements).

Question 2

Three ways to form a mineral

Answer 2

1. Crystallization from a magma
2. Crystal growth in the solid-state (minerals changing after nucleation)
3. Precipitation from solution

Question 3

Crystallization from a magma

Answer 3

A mechanism by which crystals form. As magma cools, minerals begin to form.

Question 4

Crystal growth in the solid state

Answer 4

A mechanism by which crystals form. Minerals change after initial nucleation.

Question 5

Precipitation from Solution

Answer 5

A mechanism by which crystals form. This occurs when a substrate is reached in an aqueous solution. (Example: salt in salt lakes)

Question 6

Ionic Bonding

Answer 6

A type of bonding between cations (positively charged) and anions (negatively charged). Most minerals are ionicly bonded.

Question 7

Covalent Bonding

Answer 7

Covalent bonds are formed when electrons are shared.

Question 8

Classes of Minerals

Answer 8

Native Elements
Oxides
Halides
Carbonates
Sulfates
Silicates
Sulfides

Question 9

Oxides defining Anion

Answer 9

Oxygen ion O2-

Question 10

Halides defining ion

Answer 10

Chlorine Cl-, flourine F-, Bromine Br-, Iodide (I-)

Question 11

Carbonates defining ion

Answer 11

Carbonate ion (CO3 2-)

Question 12

Sulfates defining ion

Answer 12

Sulfate ion SO4 2-

Question 13

Silicates defining ion

Answer 13

Silicate ion SiO4 4-

Question 14

Sulfides defining ion

Answer 14

Sulfide ion S2-

Question 15

Silicates

Answer 15

The most abundant mineral (composing 95% of the minerals in the crust).

Feldspar (60%) and Quarts (15%) are the most abundant.

These minerals are classified by:

• the linking of silica tetrahedral
• their composition (ferromagnesian or aluminosilicates, or the type of interlayer cations (in feldspars - Na+, Ca2+, K+)

Question 16

Ferromagnesian Silicates

Answer 16

Silicates rich in Fe or Mg

Question 17

Aluminosilicate

Answer 17

Silicates rich in Al or Si

Question 18

Silicate ion

Answer 18

A central silicate ion surrounded by 4 oxygen atoms in a tetrahedron - this will form in a silicate tetrahedra arrangement

Question 19

Polymerize Silicate formation types

Answer 19

The (SiO4)4- anion can polymerize by sharing oxygen corners into pairs, rings, chains, sheets, or frameworks

Question 20

Silicate Structures

Answer 20

Single Tetrahedron, Single Chain, Double chain, Sheet, Network/Framework

Question 21

Ferromagnesian Minerals

Answer 21

Minerals are composed of Iron or Magnesium ions which serve as cations to bind the silica tetrahedra together (usually dark in colour).

Very easy to weather as they form out of magma at very high temperatures. Typically, they weather (ex: oxidize) to form Fe/Al hydroxides as secondary mienrals.

Question 22

Aluminosilicates

Answer 22

Also known as clays, such as feldspars. Clay particles are formed from the alteration of aluminum silicates in both felsic and mafic rocks.

Question 23

Properties most clay minerals have in common

Answer 23

Most clay minerals are:

1. Proposed of predominantly silica and aluminum
2. less than 2 micrometers in size (clay fraction)

Question 24

Non-SIlicates are classified to:

Answer 24

Non-silicates are classified in according to:

1. the chemical composition of the anion
2. the type of cation

Question 25

Common non-silicate minerals

Answer 25

native elements, carbonates, sulfates, sulfides, oxides, hydroxides, halides

Question 26

Carbonates

Answer 26

The carbonate ion (CO3 2-) consists of a carbon atom surrounded by 3 oxyden anions which are linked together by cation (Ca2+, Mg2+, Fe2+, or Mn2+).

Question 27

Calcite

Answer 27

The most abundant carbonate, CaCO3, and is a constituent of limestone and marble.

Question 28

Carbonates examples

Answer 28

Ca2+ calcite Mg2+ dolomite Fe2+ siderite Mn2+ rhodochrosite

Question 29

Sulfates

Answer 29

The basic structure of a tetrahedron is made up of a central sulfur atom surrounded by 4 oxygen anions (SO4 2-). Example: gypsum (CaSO4)

Question 30

Gypsum

Answer 30

CaSO4 Forms in evaporitic environments

Question 31

Sulfides

Answer 31

Consists of the sulfide anion (S2-) A chief mineral in metal ores. Example: pyrite (FeS2)

Question 32

Hydroxides and Oxides

Answer 32

Compounds in which O2- or OH- is bonded to metal cations. This group is the primary source of Fe, Al, Mn, and Ti. Generally, hydroxides form from a solution and convert into oxide phases to be more stable.

Question 33

Examples of Hydroxides and Oxides

Answer 33

``` Ferric hydroxide Fe(OH)3 Hematite Fe2O3 Magnetite Fe3O4 Gibbsite Al(OH)3 Corundum Al2O3 Mn-oxides MnO2 Rutile TiO2 ```

Question 34

Mineral Properties

Answer 34

``` Hardness Cleavage Fracture Luster Color Streak Density Crystal Habit ```

Question 35

Hardness

Answer 35

An approximate measure of how readily a mineral scratches. A mohs scale is used to measure hardness Strong chemical bonds result in hard minerals. Covalently bonded minerals are generally harder than ionically bonded minerals. The hardest mineral is diamond and the softest is talc.

Question 36

Cleavage

Answer 36

Cleavage is poor if bonds in the crystal structure are strong, and good if bonds are weak. covalent bonds generally give poor or no cleavage. ionic bonds are weaker and therefore give good cleavage.

Question 37

Fracture

Answer 37

Related to the distribution of bond strengths across irregular surfaces other than cleavage planes

Question 38

Luster

Answer 38

Tends to be glassy for ionic crystals and more variant for covalent

Question 39

Color

Answer 39

Determined by ions and trace elements. Many ionically bonded crystals are colorless. Iron tends to colour strongly. This is not a good indicator as it varies due to chemical impurities.

Question 40

Streak

Answer 40

The color of fine mineral powder is more characteristic than that of massive minerals because of uniformly small size grains. This is good for hematite as it makes a red streak.

Question 41

Density

Answer 41

Depends on the atomic weight of atoms or ions and their closeness of packing in the crystal structure

Question 42

Crystal Habit

Answer 42

Depends on the plane of a mineral's crystal structure and the typical speed and direction of crystal growth.

Question 43

Acid Test

Answer 43

If putting acid on a mineral makes it fizz, the mineral contains carbonate.

Question 44

Rocks

Answer 44

Naturally occurring aggregates of minerals