Week 2

Question 1

defining characteristics of a mineral

Answer 1

1) naturally occurring
2) solid
3) inorganic (non-living)
4) definite chemical composition
5) ordered internal structure (crystalline)

Question 2

Aggregate

Answer 2

implies that minerals are joined in such a way that the properties of each minerals are retained

Question 3

how many elements are there

Answer 3

118, and 90 naturally occuring

Question 4

Atom

Answer 4

the smallest part of matter that cannot chemically be split, an extremely small chemical that does the combining

Question 5

why are atoms neutral

Answer 5

number of electrons = number of protons

Question 6

covalent bonding

Answer 6

the sharing of an electron pair between two atoms

Question 7

ionic bonding

Answer 7

the electrostatic force of attraction between a positively charged metal ion and a negatively charged non-metal ion

Question 8

metallic bonding

Answer 8

Occurs in metals in pure, native form (e.g copper, gold, and silver)… Nuclei of metal atoms “float” in a sea of electrons. This free migration of electrons accounts for strong ability of metals to conduct electricity and the ease with which metals are shaped

Question 9

intermolecular bonding

Answer 9

these bonds are very weak, produced by slight charge imbalances (“van der Waals” forces)

Question 10

Crystal Form/Habit

Answer 10

Arrangement patterns of atoms within minerals are displayed in their external crystal form. The packing arrangement of atoms within any given mineral result in a characteristic geometry of crystal faces.

Question 11

Cleavage

Answer 11

When a mineral breaks along well-defined planes. A mineral will preferentially break along planes of weaker bonding within the crystal structure

Question 12

Fracture

Answer 12

Some minerals do not have a distinct cleavage due to more uniform bond strengths throughout the crystal structure (no distinct planes of weakness).
For example, broken surfaces of quartz are scoop-shaped. The curved surfaces look like the interior of a seashell, so is called conchoidal fracture.

Question 13

Hardness

Answer 13

Measure of the resistance of minerals to being scratched. The hardness of a mineral reflects the overall strength of bonding within its crystal structure. Hardness is measured in units of Mohs scale of hardness.

Question 14

Specific Gravity

Answer 14

A number representing the ratio of the weight of a mineral to the weight of an equal volume of water

Question 15

Diaphaneity

Answer 15

Ability to transmit life. Can be transparent, translucent or opaque

Question 16

Lusture

Answer 16

the appearance or quality of light reflected from the surface of a mineral

Question 17

Metallic Lusture

Answer 17

the appearance of metal
EX. gold and pyrite

Question 18

Non-metallic Lusture

Answer 18

not having the appearance of metal
EX. fluorite, calcite and tourmaline

Question 19

Colour

Answer 19

primarily manifests the chemical content of a mineral. Also relates to the charges among ions within the mineral

Question 20

Amethyst Quartz Colour

Answer 20

This “yellow” range of wavelengths of white light is absorbed. So we see wavelengths of purple, which is the complimentary colour on the colour wheel

Question 21

Streak

Answer 21

Another way of identifying some minerals is to powder them. We do this by rubbing the mineral specimen against an unglazed porcelain plate called a streak plate
EX. Hematite (iron oxide) is redish brown

Question 22

Gemstone beauty

Answer 22

Beauty of a gem is usually based on: colour, lustre, transparency, or unusual optical properties

Question 23

The four C’s of gemstones quality

Answer 23

carat weight, colour, clarity and cut

Question 24

Durability

Answer 24

the resistance of the gemstone damage and dependent upon physical properties, such as hardness and tenacity.

Question 25

Tenacity

Answer 25

the resistance to bending and breaking

Question 26

Stability

Answer 26

Usually refers to the gem’s resistance to destruction by chemical factors. Can also refer to how well a gemstone retains its colour

Question 27

Weight

Answer 27

The carat (ct) is the standard unit of weight used in the pricing of gemstones. Due to differences in the density/specific gravity of different gems, carat weight can be misleading: EX. a one carat sapphire is much smaller than a one carat opal, and a one carat diamond is smaller than a one carat sapphire

Question 28

Rarity

Answer 28

reflects the uniqueness of natural geological processes that form them

Question 29

Demand

Answer 29

Value of certain gemstones fluctuate with trends in fashion

Question 30

Corundum

Answer 30

Usually dull in colour, Ruby and sapphire are just unusually beautiful forms of it. Specimens of corundum with exceptional clarity and colour are used as gemstones

Question 31

Asterism

Answer 31

Star pattern of light in some sapphires and rubies, resulting from the presence of inclusions of the rutile (TiO2). Play of light usually forms a six-sided star

Question 32

Three basic cuts used

Answer 32

1) Cabochon 2) Brilliant 3) Step

Question 33

Cabochon Cut

Answer 33

Simple round- to oval-shaped dome, used principally in translucent and opaque gemstones with bold colours and intermediate hardness. EX. turquoise and opal

Question 34

Brilliant Cut

Answer 34

Accentuates a gemstone’s ability to transmit, reflect and disperse light. Principally developed for diamonds. Can have up to 59 facets that are carefully angled to highlight a stone’s brilliance and light disperson

Question 35

Step Cut

Answer 35

broad table-like facet with smaller and longer rectangular facets around its edges. This type of cut emphasizes the colour of stones with a low degree of light dispersion

Question 36

Varient of Step Cut: Emerald Cut

Answer 36

Developed to reduce edge damage of emeralds and other brittle gems