Geology Midterm 1

Question 1

Rock

Answer 1

Aggregate of one or more minerals

Question 2

Mineral

Answer 2

• Inorganic
• Naturally occurring
• Crystalline solid
• Narrowly defined chemical composition
• Orderly atomic structure
• Characteristic physical properties

Question 3

Ionic, Covalent, Metallic, and Van Der Waals Bonding

Answer 3

Ionic: transfer of ions w/ opposite electrical charges attracting one another.

Covalent: Atoms share electrons.

Metallic: Extreme electron sharing, explains why metals are good conductors of heat and electricity.

Van Der Waals: Extremely weak without available electrons to form attraction (ex. Graphite)

Question 4

Cleavage-Mineral Properties

Answer 4

Breakage along planes of weakness. Alignment of bonds create these planes of weakness, not all minerals exhibit cleavage.

1. Cleavage in one direction (basal cleavage): ex. micas- biotite, muscovite.
2. Cleavage in 2 directions @ 90 degrees: ex. Feldspars- potassium feldspar and plagioclase feldspar.
3. Cleavage in 2 directions NOT at 90 degrees: ex. amphibole
4. Cleavage in 3 directions @ 90 degrees (cubic cleavage): ex. galena
5. Cleavage in 3 directions NOT at 90 degrees (rhombohedral cleavage): ex. dolomite, calcite.
6. Cleavage in 4 directions (octahedral cleavage): ex. fluorite.
7. Cleavage in 6 directions (dodecahedral cleavage): ex. sphalerite

Question 5

Fracture-Mineral Properties

Answer 5

A mineral breakage along an irregular surface. Any mineral will fracture if enough force is applied. You may have uneven or conchoidal fractures.

Question 6

Hardness-Mineral Properties

Answer 6

Resistance to scratching or abrasion.

Moh's Hardness Scale
10-Diamond
9-Corundum
8-Topaz
7-Quartz
6-Orthoclase
5-Apatite
4-Flourite 
3-Calcite
2-Gypsum
1-Talc

Question 7

Luster-Mineral Properties

Answer 7

How a mineral reflects light (metallic or non metallic).

Non Metallic: can be light or dark coloured, shiny or dull.

Metallic: Metallic luster

Question 8

Crystal Form-Mineral Properties

Answer 8

The shape a mineral will grow in (only if the mineral grows in unrestricted space-not common)

Broken Minerals DO NOT EQUAL crystals

• look to see if there is any internal weakness
• look to see if there are any fractured surfaces

Question 9

Reaction to HCl-Mineral Properties

Answer 9

Some minerals will react with dilute HCl (effervesce)

Question 10

Streak-Mineral Properties

Answer 10

The colour of the powdered form of a mineral (rub sample on porcelain)

Question 11

Color-Mineral Properties

Answer 11

Can vary in the same mineral.

Many minerals such as quartz can take on a variety of colors

Question 12

Silicates-Mineral Classes

Answer 12

The building block for silicate minerals is the silica tetrahedron.

Silica Tetrahedron: Net charge of 4, needs to bond w/ cations to balance the negative charge or O-2 ions can bond with other O-2 ions of nearby silica tetrahedron sharing the electrons

Nonferromagnesian Silicate: Si and O

Ferromagnesian Silicate: Contain Fe and sometimes MG

Question 13

Native Elements-Mineral Classes

Answer 13

Copper, Gold, Lead, Graphite

These minerals DO NOT need to bond.

Question 14

Oxides-Mineral Classes

Answer 14

Ice, hematite, corundum, magnetite.

These minerals contain O-2.

Question 15

Sulphides-Mineral Classes

Answer 15

Galena, pyrite, chalcopyrite, sphalerite

These minerals contain S-2

Question 16

Sulphates-Mineral Classes

Answer 16

Barite, gypsum, anhydrite

These minerals contain SO4

Question 17

Halides-Mineral Classes

Answer 17

Flourite, halite

These contain either Cl or F

Question 18

Carbonates- Mineral Classes

Answer 18

Calcite, Dolomite

These minerals contain CO3