MINERAL REASOURCES

Question 1

• Provide examples of things that are mined from the earth

Answer 1

o Rock slabs (eg. Granite/ metamorphic countertops, slate garden pavers)
o Gemstones
 Minerals humans have socially “agreed” are valuable and often cut (facet) to enhance mineral luster and color
o Fuels
 Fossil (peat, coal)
 Mineral (uranium)
o Precious metals
o Base metals
o Industrial minerals and materials
 Industrial minerals: not sources of fuel or metals, used for their physical and chemical properties (eg. Potash, gypsum, talc)
 Aggregate: sand, gravel, crushed stone for construction

Question 2

o Mineral deposit

Answer 2

an unusual mineral concentration, regardless of whether or not it can be extracted

Question 3

o Mineral resource:

Answer 3

a concentration of natural material that can be extracted now or in the future, includes reserves. Depending on how much data we have we can consider resources to be measures, indicated or inferred

Question 4

o Mineral reserve

Answer 4

: resources that can be determined to be extracted at a profit at the time of determination

Question 5

o Ore

Answer 5

: a naturally occurring solid material form which a valuable mineral can be extracted for a profit

Question 6

o Grade:

Answer 6

: the concentration of the desired material (mineral or element) the ore contains

Question 7

o Ore minerals are those that contain the elements of interest

Answer 7

 Oxides, sulphides, silicates, elemental metals
 Easily extractable

Question 8

o Gangue minerals

Answer 8

those that are part of the deposit but are considered waste material

Question 9

• Sedimentary (

Answer 9

eg solutions/precipitation and placer deposits)
o Placer deposits  weathering and erosion concentrate ore minerals, usually through fluvial transport

Question 10

• Magmatic

Answer 10

. Crystal settling and fractionation)
o Igneous sulfide minerals are immiscible in magmas and sink to the bottom of he magma chamber

Question 11

• Metamorphic

Answer 11

eg. Contact metamorphism and hydrothermal alteration)
o Hydrothermal  metals are concentrated in hydrothermal veins

Question 12

o Plate tectonic is the unifying theory of geology- it provides a geodynamic framework for geological phenomena

Answer 12

 Rock deformation
 Metamorphism
 Magmatism
 Climate (oceans circulation, continental elevation)

Question 13

o Deposits in time and space

Answer 13

 Mineral deposits types are not randomly distributed in tie or space- they have preferred or exclusive geological ages or tectonic settings

Question 14

 There is an association of mineral deposits with ….

Answer 14

• Particular geodynamic environments reflecting tectonic setting:
  o Convergent margins subduction, collision
  o Divergent margins  mid-ocean rides, back arc basin

Question 15

o Most of the world’s major deposits of iron

Answer 15

 Chemical sedimentary rocks- precipitation in the oceans
 Proterozoic age (dominantly 1.8-25 Ga)
 Fe in hematite (Fe2O3) and magnetite (Fe3O4)

Question 16

o Global distribution of large and giant iron formations and select smaller deposits

Answer 16

 Early Paleoproterozoic/ Neoarchean in America. Brazil, Australia and South Africa
* Little or no free oxygen

Question 17

o Formed as chemical sediments in shallow seas in the Precambrian when the atmosphere and oceans were poor in oxygen

Answer 17

 BIF resulted form changes in the iron chemistry of sea water
 Because there was little oxygen at this time, iron was present in its reduced state (Fe2+) which can readily be dissolved and transported by water soluble in water and periciptated out as layer of Fe- oxides like hematite and magnetite

Question 18

o The source of iron in IBF was hydrothermal Fe2+ emitted along ocean ridges or submarine mantle plume- related volcanism:

Answer 18

 Fe2+ was dissolved and transported in these deep water, building up over time
 Oxidation of seawater by the anoygenic photosynthesis of “iron bacterica” changes iron to its oxidized state (Fe3+)
 Fe3+ is not

Question 19

o Porphyry copper deposits

Answer 19

 Large tonnage, low grade deposits
 Worlds primary source of coper, Mo, Sn-W (+Au)
 Form at depth in magmatic arcs (2-4kms)
 The mot important source of Cu and Mo in BC (eg highland valley copper)
 Porphyritic- igneous texture, larger crystals in a finer grained groundmass
 Mineralization in veins  more veins = more ore

Question 20

o High vs low grade – refers to the concentration of the ore

Answer 20

 In general, mineral deposits which occur in veins are higher grade and mineral deposits which contain disseminated ore are low grade

Question 21

o Large low grade deposits

Answer 21

 Open pit copper mine in Canada – grade 0.4% Cu

Question 22

o Diamonds

Answer 22

 Canada is one of the largest producers of diamonds
 Diamonds are used as gems and have industrial purposes
 Diamonds form within cratons (thick, ancient portions of continental crusts) at ~150-200km depth
 Brough to the surface by Kimberlite magmas

Question 23

o Ores need to be located (exploration), obtained (extraction, and then concentrated (beneficiation/smelting/refining)

Answer 23

After mining is completed, surface and underground impacts should be remediated and the land reclaimed. Mines need to be safely closed

Question 24

o Exploration

Answer 24

 Important to determine location, size, depth, and the orientation/trend of the deposit

Question 25

 Methods to find suitable mining locations

Answer 25

• Create and review geological maps (surface and cross sectional)
• Compare area of exploration to similar environments where the mineral has been found in appropriate concentrations previously
• Visit the potential mine site to complete field studies, which might entail additional mapping, surface rock sampling, and chemical analysis

Question 26

mining depends on ..

Answer 26

 Depends on the size, shape, type, depth, and grade of the deposit

Question 27

open pit

Answer 27

o Cheaper
o Ore body is close to the surface
o Method has a lot of waste rock (gangue)

Question 28

underground mining

Answer 28

o Used for deeper deposits
o More costly
o More precise

Question 29

o Formation of coal

Answer 29

 Dead plant matter collects in oxygen poor water (swamp)
 Sediments cover organic matter, adding heat ad pressure
 Peat  lignite, brown coal  sub-bituminous coal  semi anthracite  anthracite
 Starts with moisture, volatile matter and oxygen  more calorific value, fixed carbon and carbon as more heat and pressure

Question 30

o Formation of oil

Answer 30

 Accumulation of marine microorganism
 Methane produced at low depths through anerobic bacteria
 At deep depths there is the oil window which is the T and P conditions which favor the formation of oil

Question 31

• Provide a very basic explanation of environmental impacts that might result from mining

Answer 31

o Landscape and habitat degradation
o Need to control of surface water runoff (mt Polley BC)
funding to ensure safe mine closure and restoration
o Land reclamation
 Natural ecosystem  disturbance (mining)  (restoration, rehabilitation, replacement)
o Many metals occur in nature as sulfides:
 Fe as pyrite (FeS2)
 Cu as Cu2S (chalcocite, Cu5FeS4 (bornite)
 Zn as ZnS (sphalerite)
o Trace toxic metals – calcium, arsenic
o Processing of ore releases sulfur
 Acid rain downwind of smelters
 Acid mine drainage
* Mine tailing (waste) expose sulphides to air and water
o FeS2 +h2+ O2  Fe (in water) + H2SO4 (sulfuric acid)  acid mine drainage
* Rio Tinto (red river) in SW Spain
* 5000 years of mining in this region (Cu, Ag, Au)
* pH= 2 to 2.5, red color due to iron dissolved in water
o Cyanide used to extract gold in small mines