vitamins and macro minerals 2

Mineral Resources 1 Mineral deposits are any volume of rock containing an enrichment of one or more minerals.. Mineral Resources 4 Sphalerite, galena, and chalcopyrite are ore minerals

Chapter 21: Resources of Minerals

and Energy

Introduction: Natural Resources And Human History (1)

 Over one hundred sixty thousand years ago, our

ancestors probably began to use flint, chert, and

obsidian to make tools

 Metals were first used more than 20,000 years ago

 Copper and gold were the earliest metals used.

 By 6000 years ago, our ancestors extracted copper

by smelting.

 Before another thousand years had passed, they had discovered how to smelt lead, tin, zinc, silver, and other metals.

Introduction: Natural Resources And Human History (2)

 The technique of mixing metals to make alloys came next.

– Bronze was composed of copper and tin.

– Pewter was composed of tin, lead, and copper.

 The smelting of iron came much later—about 3300 years ago.

 The first people to use oil instead of wood for fuel were the Babylonians, about 4500 years ago.

 The first people to mine and use coal were the

Chinese, about 3100 years ago.

Mineral Resources (1)

 Mineral deposits are any volume of rock containing

an enrichment of one or more minerals

 Mineral resources have three distinctive

characteristics:

 Occurrences of usable minerals are limited in

abundance and localized at places within the Earth’s crust.

 The quantity of a given mineral available in any one country is rarely known with accuracy

 Deposits of minerals are depleted by mining and

eventually exhausted.

Figure 21.1

Figure 21.2

Mineral Resources (2)

 Ore is an aggregate of minerals from which one or more minerals can be extracted profitably

 “Ore” is an economic term, whereas “mineral

deposit” is a geologic term

 The economic challenges of ore are to find it, mine

it, and refine it as cheaply as possible

 The lowest-grade ores ever mined—about 0.5

percent copper—were worked only at a time of high metal prices

Mineral Resources (3)

 In 2002, lowest grade of of mineable copper ore is closer to 1 percent.

 Over production of copper around the world,

combined with economic recession, has resulted

in the closing of many mines, particularly those exploiting the lowest grades of ores

Mineral Resources (4)

 Sphalerite, galena, and chalcopyrite are ore minerals from which zinc, lead, and copper respectively can

be extracted

 Ore minerals rarely occur alone

 They are mixed with other nonvaluable minerals,

collectively termed gangue.

dolomite.

Origin Of Mineral Deposits (1)

 All ores are mineral deposits because each of them

is a local enrichment of one or more minerals or

mineraloids

 Not all minerals deposits are ores

 In order for a deposit to form, processes must bring about a localized enrichment of one or more

minerals

Origin Of Mineral Deposits (2)

 Minerals become concentrated in five ways:

 1 Concentration by hot, aqueous solutions flowing

through fractures and pore spaces in crustal rock to form hydrothermal mineral deposits.

 2 Concentration by magmatic processes within a body of igneous rock to form magmatic mineral deposits

Origin Of Mineral Deposits (3)

 3 Concentration by precipitation from lake water or sea water to form sedimentary mineral deposits.

 4 Concentration by flowing surface water in streams or along the shore, to form placers.

 5 Concentration by weathering processes to form

residual mineral deposits.

Hydrothermal Mineral Deposits (1)

 Some solutions originate when water dissolved in magma is released as the magma rises and cools

 Other solutions are formed from rainwater or

seawater that circulates deep in the crust

 Mineral deposits formed from midocean ridge

volcanism are called volcanogenic massive sulfide

deposits.

Figure 21.3

Hydrothermal Mineral Deposits (2)

 The pyroxene-rich rocks of the oceanic crust yield solutions charged with copper and zinc

 As a result, volcanogenic massive sulfide deposits are rich in copper and zinc.

 In black smokers, the rising hydrothermal fluid

appears black due to fine particles of iron sulfide and other minerals precipitated from solution as the plume is cooled by contact with cold seawater

 The chimney-like structure is composed of pyrite,

chalcopyrite, and other ore minerals deposited by

hydrothermal solution

Hydrothermal Mineral Deposits (3)

 When a hydrothermal solution moves slowly

upward, as with groundwater percolating through an aquifer, the solution cools very slowly

 If dissolved minerals were precipitated from such a slow-moving solution, they would be spread over a large volume of rock and would not be sufficiently concentrated to form an ore

Hydrothermal Mineral Deposits (4)

 When a solution flows rapidly, as in an open

fracture, or through a mass of shattered rocks, or

through a layer of porous tephra where flow is less restricted, cooling can be sudden and can occur over short distances

 Rapid precipitation and a concentrated mineral deposit are the result.

 Veins formed when hydrothermal solutions deposit minerals in open fractures

 Many such veins are found in regions of volcanic

activity.

Figure 21.5

Hydrothermal Mineral Deposits (5)

 The famous gold deposits at Cripple Creek,

Colorado, were formed in fractures associated with

a small caldera

 The huge tin and silver deposits in Bolivia are in fractures that are localized in and around

stratovolcanoes

 Many famous ore bodies are associated with

intrusive igneous rocks

 Tin in Cornwall, England,

 Copper at Butte, Montana, Bingham, Utah, and Bisbee, Arizona.

Figure 21B1

Magmatic Mineral Deposits (1)

 The processes of partial melting and fractional

crystallization are two ways of separating some

minerals from other

 The processes involved are entirely magmatic, and

so such deposits are referred to as magmatic

mineral deposits.

Magmatic Mineral Deposits (2)

 Pegmatites formed by fractional crystallization of granitic magma commonly contain rich

concentrations of such elements as:

 Lithium.

 Beryllium.

 Cesium.

 Niobium.

Magmatic Mineral Deposits (3)

 Much of the world’s lithium is mined from

pegmatites such as those at King’s Mountain, North Carolina, and Bikita in Zimbabwe

 The great Tanco pegmatite in Manitoba, Canada,

produces much of the world’s cesium, and

pegmatites in many countries yield beryl, one of the main ore minerals of beryllium

Magmatic Mineral Deposits (4)

 Crystal settling, another process of fractional

crystallization, is especially important in

low-viscosity basaltic magma

 One of the first minerals to form is chromite, the

main ore mineral of chromium

 The dense chromite crystals settle to the bottom of the magma, producing almost pure layers of

chromite

 The world’s principal deposits of chromite are in the

Bushveld igneous complex in South Africa and the Great Dike of Zimbabwe.

Sedimentary Mineral Deposits

 The term sedimentary mineral deposits is applied

to any local concentration of minerals formed

through processes of sedimentation.

 One form of sedimentation is the precipitation of substances carried in solution

deposits:

 Evaporite deposits.

 Iron deposits.

 Stratabound deposits.

Evaporite Deposits (1)

 Evaporite deposits are formed by evaporation of

lake water or seawater

 The layers of salts precipitate as a consequence of evaporation

 Salts that precipitate from lake water of suitable

composition include sodium carbonate (Na 2 CO 3 ), sodium sulfate (Na 2 SO 4 ), and borax (Na 2 B 4 O 7 1OH 2 O).

Evaporite Deposits (2)

 Huge evaporite deposits of sodium carbonate were laid down in the Green River basin of Wyoming

during the Eocene Epoch

 Oil shales were also deposited in the basin.

 Borax and other boron-containing minerals are

mined from evaporite lake deposits in Death Valley and Searled and Borax Lakes, all in California; and

in Argentina, Bolivia, Turkey, and China

Evaporite Deposits (4)

 Low-grade metamorphism of marine evaporite

deposits causes another important mineral, sylvite (KCl), to form from carnallite

 Marine evaporite deposits are widespread

 In North America, for example, strata of marine

evaporites underlie as much as 30 percent of the land area.

Evaporite Deposits (5)

 Marine evaporites produce:

 Most of the salt that we use.

 The gypsum used for plaster.

 The potassium used in plants fertilizers.

Figure 21.6

Iron Deposits (1)

 Sedimentary deposits of iron minerals are

widespread, but the amount of iron in average

seawater is so small that such deposits cannot have formed from seawater that is the same as today’s seawater

Iron Deposits (2)

 All sedimentary iron deposits are tiny by

comparison with the class of deposits characterized

by the Lake Superior-type iron deposits

 These remarkable deposits, mined principally in

Michigan and Minnesota, were long the mainstay

of the U.S steel industry.

 They are declining in importance todaybecause

imported ore is replacing them.

 They are of early Proterozoic age (about 2 billion years or older).

Iron Deposits (3)

 They are found in sedimentary basins on every craton

(Labrador, Venezuela, Brazil, Russia, India, South

Africa, and Australia).

 They appear to be the product of chemical precipitation.

 They are interbedded layers of chert and several different kinds of iron minerals.

 The cause of precipitation remains uncertain

Iron Deposits (5)

 Two additional processes can form iron ore:

secondary enrichment and can produce ores containing as

much as 66 percent Fe

is through metamorphism

the gangue becomes easier and cheaper.

iron carbonate minerals originally present can be replaced by magnetite or hematite, both of which are desirable ore minerals.

Figure 21.7

Iron Deposits (5)

 Ore grade is not increase by metamorphism,

 The changes in grain size and mineralogy transform the sedimentary rock into an ore.

 Iron ores formed as a result of metamorphism are

called taconites, and they are now the main kind of

ore mined in Lake Superior region

 The sulfide mineral layers are enclosed by and

parallel to the sedimentary strata in which they

occur

 For this reason, they are called stratabound mineral

deposits.

Figure 21.8

Stratabound Deposits (2)

 Most stratabound deposits are diagenetic in origin

 Stratabound deposits form when a hydrothermal

solution invades and reacts with a muddy sediment

 The famous copper deposits of Zambia, in central Africa, are stratabound deposits

 The world’s largest and richest lead and zinc deposits are also stratabound:

– Broken Hill, Australia.

– Mount Isa in Australia.

– Kimberley in British Columbia.

Figure 21.9

Figure 21.10

Placers (2)

 The most important minerals concentrated in

placers are gold, platinum, cassiterite (SnO2), and diamond

 More than half of the gold recovered throughout all

of human history has come from placers

Placers (3)

 The South African fossil placers are a series of gold-bearing conglomerates.

shallow marginal waters of a marine basin.

minerals.

discovered anywhere else

(11,800 ft).

Residual Mineral Deposits (1)

 Chemical weathering leads to mineral concentration through the removal of soluble materials and the

concentration of a less soluble residue

 A common example of a deposit formed through

residual concentration is bauxite

Residual Mineral Deposits (2)

 Bauxites are:

 The source of the world’s aluminum.

 Concentrated in the tropics because that is where lateritic weathering occurs.

 Found in present-day temperate conditions, such as France, China, Hungary, and Arkansas, where the climate was tropical when the bauxites formed

 Not found in glacial regions.

Residual Mineral Deposits (3)

 More than 90 percent of all known bauxite deposits formed during the last 60 million years,

 All of the very large bauxite deposits formed less than 25 million years ago

Residual Mineral Deposits (4)

 Many of the world’s manganese deposits have been formed by secondary enrichment of low-grade

primary deposits, particularly in tropical regions

Secondary enrichment zones are produced by

deposition of soluble minerals near the groundwater table, leached from mineral deposits present near

the surface

 One of the largest nickel deposits ever found, in

New Caledonia, was formed by secondary

enrichment

Residual Mineral Deposits (5)

 Secondary enrichment has led to large deposits in the arid southwestern United States and desert

regions of northern Chile of:

 Pyrite (FeS 2 ).

 Chalcopyrite (CuFeS 2 ).

 Chalcocite (CuS 2 ).

Useful Mineral Substances (1)

 Excluding substances used for energy, there are two broad groups of useful minerals:

 Metallic minerals, from which metals such as iron,

copper, and gold can be recovered.

 Nonmetallic minerals, such as salts, gypsum, and clay.

Useful Mineral Substances (2)

 Geochemically abundant metals include:

Useful Mineral Substances (3)

0.1 percent by weight of the crust.

 They are present exclusively as a result of atomic

substitution.

cobalt, and copper) can readily substitute for

more common atoms (such as magnesium and

calcium).

Useful Mineral Substances (4)

sulfides.

 A few, such as the ore minerals of tin and tungsten, are oxides;

hydrothermal or magmatic mineral deposits.

Figure 21.12

Fossil Fuels (1)

 The term fossil fuels refers to the remains of plants

and animals trapped in sediment that can be used for fuel

 The kind of sediment, the kind of organic matter,

and the processes that take place as a result of burial and diagenesis, determine the kind of fossil fuel that forms

Fossil Fuels (2)

 In the ocean, microscopic phytoplankton and

bacteria are the principal sources of trapped organic matter that are transformed (mainly by heat) to oil and gas

 On land, trees, bushes, and grasses contribute most

of the trapped organic matter, forming coal rather than oil or natural gas

Fossil Fuels (3)

 In many marine and lakes shales, burial

temperatures never reach the levels at which the original organic molecules are converted into oil and natural gas

 Instead, an alteration process occurs in which wax-like substances containing large molecules are formed.

 This material, which remains solid, is called kerogen,

and it is the substance in so-called oil shale.

Coal (1)

 Coal is the most abundant fossil fuel

 It is the raw material for nylon, many other plastics, and a multitude of other organic chemicals

 Through coalification, peat is converted to lignite, subbituminous coal, and bituminous coal.

 Anthracite is a metamorphic rock.

Figure 21.13

Coal (3)

 The greatest period of coal swamp formation

occurred during the Carboniferous and Permian

periods, when Pangaea existed

 These periods produced the great coal bed of Europe and the eastern United States.

 The second great period of coal deposition peaked during the Cretaceous period but commenced in the early Jurassic and continued until the mid-Tertiary

Petroleum: Oil and Natural Gas

 The major use of oil really started about 1847, when a

merchant in Pittsburgh, Pennsylvania, started bottling and selling rock oil as a lubricant.

 In 1852, a Canadian chemist discovered kerosene, a

liquid that could be used in lamps.

 In Romania in 1856, workers were producing 2000