rock cycle and minerals (LEC 2)

Question 1

two broad areas of geology

Answer 1

historical geology
physical geology

Question 2

sub-disciplines of geology (6)

Answer 2

Structure Geology
Environmental Geology
Geochemistry
Paleontology (biology)
Volcanology
Hydrogeology

Question 3

rock is an aggregation of minerals, what is an aggregation

Answer 3

each mineral retaining its own identity

Question 4

what causes weathering

Answer 4

Weathering:
* wind
* water waves
* running water

Question 5

what is lithification

Answer 5

lithification: compaction and cementation

Question 6

what is metamorphism

Answer 6

metamorphism: change in chemical and physical properties due to temperature and pressure

Question 7

what are the five requirement to be officially a mineral

Answer 7

1. naturally formed
2. solid, at surface temperature and pressure
3. crystalline structure, regular interior structure (its atoms must be
   arranged in definite pattern)
4. inorganic
5. chemical composition either fixed or varies within certain limits

Question 8

most minerals are a combination of two or more elements, some minerals consist entirely from one element, name some

Answer 8

diamond and graphite are made from carbon, gold, sulphur

Question 9

most minerals are a combination of two or more elements joined (via chemical bonds) to form…….

Answer 9

a compound

Question 10

most minerals are a combination of two or more elements joined (via_________) to form a compound

Answer 10

chemical bonds

Question 11

types of chemical bonds

Answer 11

1. ionic bonding
2. covalent bonding
3. metallic bonding
4. van der waals bonding

Question 12

strongest chemical bond

Answer 12

covalent bonds

Question 13

what are polymorphs

Answer 13

minerals that have the same chemical
composition but different structure
which results in different physical
properties

Question 14

example of polymorphs

Answer 14

graphite and diamond (both consist of carbon)

Question 15

minerals can be transformed from one to another if the surrounding ________ and ________ changed

Answer 15

temperature and pressure

Question 16

how can we identify minerals

Answer 16

how it looks (color, luster), breaks,
feels, smells, tastes

Question 17

why do we use physical properties, not chemical properties or the interior structure

Answer 17

because the chemical composition and/or interior structure are difficult to determine without sophisticated equipment

Question 18

what is lustre

Answer 18

the quality of light reflection from the surface of a mineral

Question 19

what does vitroeus mean

Answer 19

bright as in glass and it is transparent

Question 20

although colour is often obvious, it is not always useful in mineral identification, why and give an example of a mineral

Answer 20

slight impurities in the mineral give variety of colors
fluorite and quartz

Question 21

what is a streak

Answer 21

• it is the color of mineral in powdered form
• often useful in mineral identification
• scratching the mineral across a steak plate

Question 22

metallic minerals have a ________ streak
nonmetallic minerals have a ________streak

Answer 22

dark
light coloured

Question 23

what is a crystal habit

Answer 23

crystal habit refers to the external expression on a mineral that
reflects the orderly internal structure

Question 24

do all minerals have crystal habit

Answer 24

no, when mineral formation is interrupted by space restrictions, it will not have crystal habit, i.e. the crystal faces will not be similar to the internal structure

Question 25

what is hardness

Answer 25

a measure of resistance to abrasion or scratching by other substances

Question 26

describe the moh’s scale

Answer 26

> 5.5 …………… hard
3 to 5.5 ……… moderate
< 3 ……………. soft

Question 27

mohs scale of a fingernail

Answer 27

2.5

Question 28

mohs scale of a penny

Answer 28

3.5

Question 29

mohs scale of a construction nail

Answer 29

5.5

Question 30

what is a cleavage

Answer 30

the tendency of mineral to break along
plane(s) of weak bonds, they have unequal chemical bonds in all directions

Question 31

what is a fracture

Answer 31

the tendency of mineral to break irregularly,
producing uneven fracture, they have equal chemical bonds in all directions

Question 32

name some uncommon physical properties of minerals

Answer 32

magnetism
reaction with HCl
taste
odour
feel

Question 33

how many elements make up more than 98% of the of earth’s crust and which two make up the most

Answer 33

8
oxygen and silicon

Question 34

minerals are classified into small number of groups (7 groups) based on their chemical composition, silicates is one of them. what are the types of silicates

Answer 34

ferromagnesian: minerals that contain iron and magnesium
nonferromagnesian: minerals that don’t contain iron and magnesium