chapter 30 to 35
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Applied mineralogy. Chapter 30 to 35. Introduction to applied mineralogy. Practical application of mineralogical knowledge Mineralogy – major economic significance - PowerPoint PPT PresentationTRANSCRIPT
Chapter 30 to 35
Applied mineralogy
Introduction to applied mineralogy
Practical application of mineralogical knowledge
Mineralogy – major economic significance Gemology (Ch 31), mineral prospecting,
mineral extraction, chemical plants, cement industry (Ch 32), medicine & environmental mineralogy (Ch 33)
Growing field with developing needs – new branches of applied mineralogy develop
Indispensable in geology and petrology
Chapter 30Metalliferous mineral
deposits Prospecting mineralogy Economically important minerals Geological setting of metal deposits
Convergent margins Divergent margins Precambrian shields Sedimentary basins
Chapter 30Prospecting mineralogy
Occurrence and identification of mineral deposits, determine mineralogical composition to classify and determine extractability
Traditionally rely on visual identification in field and sample collection for laboratory investigations Mineralogical features primary criteria for prospecting
Currently more sophisticated analytical techniques Mineralogy knowledge integrated with geochemistry,
petrology and structural geology Mineralogical prospecting partly replaced by remote
sensing techniques Use electromagnetic spectrum reflected from different type of
minerals on earth surface Spatial distribution of mineral types identified on large scale Especially useful in iron and gold deposits
Chapter 30Economically important
minerals Table 30.1 and 30.2 Metalliferous minerals (Chapter 30)
Ferrous metals: Fe, Mn, Ni, Cr, Si, Mo, Co, W Nonferrous base metals: Cu, Zn, Pb, Sn, Hg Nonferrous light metals: Al, Mg, Ti, Be Precious metals: Au, Pt, Ir, Ag
Gemstones (Chapter 31) Diamond Colour gems: Corundum, beryl, tourmaline, topaz
Cement minerals (Chapter 32) Calcite, clay, gypsum
Chapter 30Metal deposits
Many metal deposits are related to RECENT plate tectonic activity
Convergent margins Melting of subducting sediments
along continental shelf produce volcanism and batholithic intrusions
Igneous activity drives hydrothermal processes
Co and Mo, Hg Divergent margins
Largest magma extrusions Seawater penetrates seafloor, heat up,
react with basalt and becomes acidic Acidic water dissolves Cu, Pb, Zn, Co,
Mn as trace elements from basalt, transport metals and concentrate them when precipitated as sulfides and oxides when in contact with cold seawater (VMS deposits)
Chapter 30Metal deposits (cont)
Precambrian shields Primary deposits of Cr, Ni, Pt much
older Orthogneisses and mafic to
ultramafic volcanics (greenstone belts) occur on these shields
Komatiites: ultramafic, very high T magma from great depths
Gold veins at contact with komatiites and surrounding granite – Witwatersrand (placer derived from above)
Layered chromite – Bushveld Complex: Cr, Pt, Cr-magnetitie, V
Sedimentary basins BIFs: Algoma-type and Superior-type Algoma: submarine hot springs
release Fe-rich hydrothermal solutions in sedimentary basins alternated with Si-rich layers
Superior-type: no volcanism, associated with limestones, formed at shallow-water coastal environments, Fe and Si layers alternatively brought from deep ocean to coast by upwelling currents
Chapter 30Metal deposits
Chapter 31Gemstones
Introduction Instruments used by gemologists Important gems Gemstone enhancements Crystal synthesis
Chapter 31Introduction
Def: minerals highly valued for beauty, durability and rarity
Most precious gems exceed value of same mass of gold by 3000 times
Many gems artificially produced for a fraction of the price
Gems mostly permanent, BUT: some coloured gems could lose colour due to sunlight or heat exposure.
Small worldwide production in kg, but yearly value equals that of cement production.
Chapter 31Gemology instruments
Similar to mineralogical instruments – but has to be non-destructive.
Energy dispersive X-ray fluorescence on gem surfaces
NB – binocular gemological microscope Dark / light field illumination to check
inclusions, growth features, treatment and synthesis
Gem refractometer, spectroscope, polariscope
Chapter 31Important Gems
Diamonds – upper mantle, kimberlites Emerald – hydrothermal systems Ruby, sapphire – high T environments: alkaline
magmas and aluminous metamorphic rocks Aquamarine, topaz, tourmaline - pegmatites
Chapter 31Gemstone enhancements Improve appearance by:
Cutting Heating to improve colour – often
produce damage and often non-permanent
Filling cracks – can wear off, not as durable
Dying – not stable, do not penetrate entire crystal
Radiation to induce colour – also not always permanent
Chapter 31Crystal synthesis
Large market for synthetic gems, also for industrial use
Different methods Powder flame fusion: ruby and sapphire Czochralski melt growth: rubies for
lasers, silicon crystals, garnets Flux growth: emeralds Hydrothermal growth: quartz Ultra-high pressure: diamond
Chapter 32Cement minerals
Significance of cement Some features of nonhydraulic
cements Portland cement Some problems with concrete
Chapter 32Significance of cement
Concrete is most widely used structural material in world today.
1 billion tonnes of Portland cement converted into 11.5 billion tonnes of concrete 5 x more than steel consumption
Much weaker than steel, but preferred Resistance to water Formed into many shapes and sizes
Cheapest and most readily available building material
Concrete: cement + aggregate ( sand, gravel and/or crushed rock)
Chapter 32Types of cement
Non-hydraulic cements Harden by calcination; not resistant to
water Minerals: Gypsym from anhydrite;
calcite from lime Hydraulic cements
Harden by reacting with water; water resistant
Portland cement: Ca-silicates and Ca-carbonates, with Al- and Fe-oxides
Chapter 32Concrete problems
Sulfate attack Sulfate in soil, seawater, acid rain Cracking, permeability increase, loss of strength Mainly when gypsum form when sulfate react with
cement minerals and has a volume increase Alkali-silica reaction
Siliceous minerals: opal, microcrystalline quartz, deformed quartz are open for this reaction with alkali ions in pore system of cement: destroys cement, increase permeability, swellling
Corrosion Steel bars corroded when solution enters concrete;
corrosion products have high volume – cause cracking around steel
Chapter 33Minerals and human
health Mineral-like materials in human
body Apatite and other phosphate
minerals Mostly as important part of bones and
teeth Also occurs as abnormal growths as
kidney, urinary, and gall stones; tumors; in lungs, glands, heart and arteries
Calcite, aragonite and vaterite Constructive part of teeth Abnormal growths in glands, tumors,
kidneys and lungs Magnetite, hematite, goethite,
lepidocrocite Urinary bladders
Also oxalates, urates and other organic compounds
Chapter 33Minerals and human
health Minerals in nutrition
Halite – common mineral consciously ingested by humans
Also barite – filling in chocolate Kaolinite – in ice creams – stabilize when
melting
Chapter 33Minerals and human
health Minerals in nutrition (continued)
Inorganic compounds known in market as ‘minerals’ – important as nutritional additives along with vitamins
Macrominerals: Ca, Cl, Mg, P, K, Na, S – needed in large quantities
Microminerals: Cr, Co, F, Fe, Mn, Mo, Zn – needed in trace quantities
Mostly derived from ‘real minerals’ Deficiency as well as too high
concentration of most of these can cause severe health effects
Chapter 33Minerals and human health Minerals as health hazards Many minerals has been documented to
cause pulmonary diseases: Riebeckite – mesothelioma Grunerite, actinolite, antophyllite, tremolite
and chrysotile – asbestosis Quartz – silicosis Coal - emphysema (pneumoconiosis)
Chemical contamination by mining Atmosphere, water (ground and surface)
Chapter 34Minerals in the solar
system Current theory for universe: ‘Big Bang’
produce elements: Firstly light elements: He and H During cooling denser matter condense and
collapse – nuclear fusion: up to Fe and Ni Stellar explosions – supernovae: heavier
elements Meteorites
NB information on solar space mineralogy Different types: chondrites, achondrites, iron
and stony iron meteorites Many unique meteorite minerals, but also
minerals common to the earth
Chapter 35Mineral composition of
earth Crust
Heterogenous: Sedimentary and igneous rocks; oceanic and continental crust
Feldspars, pyroxenes, quartz, olivine, amphiboles, micas > 80% of crust
Mantle Uniform Olivine, enstatite, Cr-diopside and augite,
spinels, amphiboles, Ti-phlogopite, garnet, plagioclase, apatite, diamonds, chromite
Core Heavy elements