Metals

Question 1

Resource

Answer 1

A useful and valuable natural resource

Question 2

Reserve

Answer 2

The amount of a resource which can be extracted at a profit using existing technology

Question 3

Ore

Answer 3

A mineral containing valuable metals

Question 4

Gangue mineral

Answer 4

Low value waste material

Question 5

Average crystal abundance

Answer 5

The amount of metal in ‘average’ continental crust

Question 6

Cut off grade

Answer 6

Minimum grade that is economic to mine

Question 7

Concentration factor

Answer 7

The amount by which the medal is concentrated to make an ore deposit

Question 8

Why are reserves difficult to estimate accurate?

Answer 8

Unexpected faulting, demand fluctuations, improvement in technology

Question 9

How do placer deposits form?

Answer 9

Mechanical and chemical weathering breaks down exposed mineral veins and minerals are then transported, sorted and concentrated when deposited

Question 10

Name 4 properties of placer deposits

Answer 10

Dense
Hard
Little or no cleavage
chemically resistant

Question 11

How are placer deposits mined?

Answer 11

Dredging

Hydraulic mining

Question 12

How do gravity gravity survey indicate metal mineral deposits?

Answer 12

Dense rock (ore/mafic)=positive anomaly
Less dense rocks(silicic)= negative anomaly

Question 13

How do magnetic surveys indicate metal mineral deposits?

Answer 13

Minerals rich in iron produce positive magnetic anomalies

Question 14

How do electrical resistivity surveys indicate metal mineral deposits?

Answer 14

Metal ores=low resistivity

Question 15

Galena

Answer 15

Lead ore

Question 16

Casserite

Answer 16

Tin ore

Question 17

Magnetite

Answer 17

Iron ore

Question 18

Spalerite

Answer 18

Zinc ore

Question 19

Bauxite

Answer 19

Aluminium ore

Question 20

Chalcopyrite

Answer 20

Carbon ore

Question 21

Secondary enrichment

Answer 21

Oxidising conditions above water table convert copper sulphides into soluble copper sulphates.
Copper sulphates leached out and move down towards water table.
On meeting reducing conditions at water table copper sulphates react and are precipitated out as copper sulphides

Question 22

Concentration factor equation

Answer 22

Concentration of metal ore/ average crystal abundance

Question 23

Dredging

Answer 23

Material is scraped or sucked from a river or sea bed

Question 24

Hydraulic mining

Answer 24

The use of high power water jets to dislodge material

Question 25

Gravity settling

Answer 25

magma cools, minerals with high melting points crystallise out first. minerals with high density sink towards base of intrusion, forming a cumulate layer enriched with metals

Question 26

where do placer deposits form? x5

Answer 26

fast flowing stream joins a river
plunge pool in river bed
projections in stream bed
inside of meander bends
on a beach

Question 27

what are the pros and cons to dredging and hydraulic mining?

Answer 27

pros- less waste produces 
cons-scars landscape
noise and dust
stirred up silt=surface water pollution 
quickly exhausted

Question 28

what are the aims of exploration drilling? x4

Answer 28

what ores are present
grade
amount of gangue
depth and extent of ore body

Question 29

open cast mining

Answer 29

if ore is relatively close to the surface it is more economical to remove the overburden by quarrying

Question 30

pros of open cast mining x6

Answer 30

low cost
efficient
small workforce 
less expensive machinery 
no ventilation needed 
thinner ore bodies can be mined at a profit

Question 31

underground mining- stope

Answer 31

shafts drilled vertically downwards, then drive horizontal levels through to the orebody.

Question 32

longwall retreat

Answer 32

2 horizontal roadways driven out to furthest point to be mined. Roadways connected with a ‘longwall’. Shearer cuts seam by moving to and fro along face, removing slices of coal onto a conveyor belt up to the surface. Hydraulic supports hold up roof.

Question 33

geochemical anomaly

Answer 33

a concentration of a metal above its normal background value

Question 34

how can metal be found in a stream survey?

Answer 34

downstream= anomalous values
upstream of source= normal values
size of anomaly decreases downstream due to dilution

Question 35

how can metal be found in a soil survey?

Answer 35

soil samples on top and downslope of source will have anomalous metal values.
soil sample upslope of source will have normal metal values