Modul 5a - Minerals, definition & classes.pdf

7/25/2019 Modul 5a - Minerals, definition & classes.pdf

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Minerals


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Definition

What is a Mineral?What is a Mineral?

A mineral is a naturally formed inorganic crystalline solidA mineral is a naturally formed inorganic crystalline solidwith a definite chemical composition and identifyingwith a definite chemical composition and identifying

physical propertiesphysical properties naturally formednaturally formed

formed by geologic processes in nature, not by humansformed by geologic processes in nature, not by humans

inorganicinorganic was never alivewas never alive

crystalline solidcrystalline solid

a solid composed of atoms arranged in a repeating orderlya solid composed of atoms arranged in a repeating orderlyframeworkframework

definite chemical compositiondefinite chemical composition a homogeneous chemical compound with a chemical formulaa homogeneous chemical compound with a chemical formula

distinctive, identifying physical propertiesdistinctive, identifying physical properties


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Definition

What is a Mineral?What is a Mineral?

Is water a mineral?Is water a mineral?

Why or why not?Why or why not? Is ice a mineral?Is ice a mineral?

Why or why not?Why or why not?

Is glass a mineral?Is glass a mineral? Why or why not?Why or why not?

Is gold a mineral?Is gold a mineral?

Why or why not?Why or why not? Is steel a mineral?Is steel a mineral?

Why or why not?Why or why not?


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Definition

Mineral is a naturally occurring inorganic element orcompound having orderly internal structure and

characteristic chemical composition, crystal form, and

physical properties

Pertanyaan:

Apakah lampu kristal tergolong mineral?

Bagaimana dengan tubuh kekurangan mineral?

Air mineral?


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Definition

Mineral is a structurally homogeneous solid of definitechemical composition, formed by the inorganic

processes of nature.

Whitten, DGA and Brooks, JRV. 1977. The Penguin Dictionary of

Geology. Middlesex: Penguin Books. p. 293.


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Definition

This definition includes ice as a mineral, but excludes

coal, natural oil and gas. The only allowable exception

to the rule that a mineral must be solid is native

mercury (quicksilver), which is liquid.

Definite chemical composition is not synonymous with

fixed or constant composition, since many minerals

have compositions which are variable between certain

limits, which are defined in terms of end members: e.g.

the composition of the common olivines is expressible in

terms of the two compounds, Mg2SiO4 (forsterite) and

Fe2SiO4 (fayalite). The general rule is that minor

variations of composition which do not markedly alter

fundamental properties are discounted


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Definition

Structurally homogeneous implies that the fundamental

atomic structure is continuous and constant through the

mineral unit, e.g. in silicates the silicon-oxygen lattice

will be constant in characters, although the interstitialcations may vary in different parts of the lattice

Although strictly of organic origin, the constituents of

many limestones, siliceous rocks, and beddedphosphate deposits are treated as though they were true

mineral species

Whitten, DGA and Brooks, JRV. 1977. The Penguin Dictionary of

Geology. Middlesex: Penguin Books. p. 293-294.


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Electron-bearing shells

Model of Oxygen

Review


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Review

2 protons in nucleus

10 protons in nucleus

Model of Helium (He)

Model of Neon (Ne)


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Model of Sodium (Na+)

Model of Chlorine (Cl-)

Review


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Ionic Bonding:

Electron Transfer

Review

Sodium (Na)

Sodium(Na+) ion

Chlorine(Cl ) ion

Chlorine (Cl)

Model of crystalline structure of Halite (salt)


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Mineral Structures and AtomsReview

Model of crystalline structure


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Elemental Abundances in Continental CrustElemental Abundances in Continental Crust


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ELEMENT YANG MELIMPAH DI KERAK BUMI

Element Simbol % Berat % Volume % Atom

Oksigen O 46,6 93,8 60,5

Silikon Si 27,7 0,9 20,5

Aluminium Al 8,1 0,8 6,2

Besi Fe 5,0 0,5 1,9Kalsium Ca 3,6 1,0 1,9

Sodium Na 2,8 1,2 2,5

Potasium K 2,6 1,5 1,8

Magnesium Mg 2,1 0,3 1,4Semua elemwnt lain 1,5 - 3,3


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Mineral ClassesMineral Classes

Silicate Mineral GroupSilicate Mineral Group

NonNon--silicate Mineralsilicate MineralGroupGroup

Sili t Mi l G


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Silicate Mineral Groups

Silicate minerals (sil icates) are composed of silica tetrahedra (SiO44-)

For sil ica tetrahedra to be stable, they must either: be balanced by positive ions,

share oxygens with adjacent silica tetrahedra, or

substitute one or more Al 3+ for Si 4+ Compositions of the silicates

Mafic composition

Is rich in magnesium, iron, and/or calcium Intermediate composition

Is compositionally between mafic and felsic

Is rich in feldspar and/or silica (quartz)

Felsic composition

Is rich in feldspar and/or silica (quartz)

All the common rock-forming minerals are silicate mineral



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The Silica TetrahedronThe Sil ica Tetrahedron

(composed of 4 oxygen atoms surrounding 1 sil icon atom)(composed of 4 oxygen atoms surrounding 1 sil icon atom)



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Tw oTw o

I l l u s t r a t i o n s I l l u s t r a t i o n s

o f t h e o f t h e SiS iOO

44

T e t r a h e d r o n T e t r a h e d r o n



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Single Island SilicatesSingle Island Sil icates

(ex.: olivine)(ex.: olivine)

Single Chain Sil icatesSingle Chain Silicates

(ex.: augite pyroxene)(ex.: augite pyroxene)




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Single Chain Silicates: The Pyroxenes (e.g., augite)Single Chain Silicates: The Pyroxenes (e.g., augite)



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Double Chain Silicates: The AmphibolesDouble Chain Silicates: The Amphiboles

(e.g., hornblende)(e.g., hornblende)

Sheet Silicates: The MicasSheet Silicates: The Micas



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Sheet Silicates: The MicasSheet Silicates: The Micas

(e.g., biotite, muscovite, and the clays)(e.g., biotite, muscovite, and the clays)Silicate Mineral Groups

Example:Clay groupsMica groups

Because of weak bonds,mica splits asily between

sandwiches

Positive ions, sandwiches

between two sheetssilicate layers

Sheet silicate structure

Framework Silicates:Framework Silicates:



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Framework Silicates:Framework Silicates:(potassium feldspar, sodium and calcium plagioclase feldspar, qu(potassium feldspar, sodium and calcium plagioclase feldspar, quartz)artz)




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The Common RockThe Common Rock--Forming Silicate MineralsForming Silicate Minerals


Non-silicate Mineral Groups


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Non silicate Mineral Groups

Native ElementsNative Elements: consist of only one element.: consist of only one element. Au (gold), Ag (silver), Cu (copper), S (sulfur), C (graphite,Au (gold), Ag (silver), Cu (copper), S (sulfur), C (graphite,

diamond)diamond)

OxidesOxides: contain O: contain O 22-- FeFe22OO33 (hematite), Fe(hematite), Fe33OO44 (magnetite), Al(magnetite), Al22OO33 (corundum)(corundum)

CarbonatesCarbonates: contain CO: contain CO3322--

CaCOCaCO33 (calcite), CaMg(CO(calcite), CaMg(CO33))22 (dolomite)(dolomite) SulfidesSulfides: contain S: contain S 22--

FeSFeS22 (pyrite), PbS (galena), CuFeS(pyrite), PbS (galena), CuFeS22 (chalcopyrite)(chalcopyrite)

SulfatesSulfates: contain SO: contain SO44

22--

CaSOCaSO44.2H.2H22O (gypsum), BaSOO (gypsum), BaSO44 (barite)(barite)

HalidesHalides: contain F: contain F 11--, Cl, Cl 11--, Br, Br 11--, or I, or I 11--

NaCl (halite), KCl (sylvite), CaFNaCl (halite), KCl (sylvite), CaF22 (fluorite)(fluorite)



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Native CopperNative Copper

How do minerals form?


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By crystallization from magma (molten rock material)By crystallization from magma (molten rock material)

a saturation responsea saturation response

By crystallization (precipitation) from aqueous fluidsBy crystallization (precipitation) from aqueous fluids

a saturation responsea saturation response

By chemical reaction withBy chemical reaction with

magmatic fluidsmagmatic fluids

hydrothermal fluidshydrothermal fluids

water during weatheringwater during weathering By solid state transformations (metamorphism)By solid state transformations (metamorphism)

changes crystal formchanges crystal form

moves ions to new locationsmoves ions to new locations promotes growth along the edges of mineral grains (crystals)promotes growth along the edges of mineral grains (crystals)

at the expense of their neighboring mineral grainsat the expense of their neighboring mineral grains



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Crystallization of Minerals in Cavit ies: GeodesCrystallization of Minerals in Cavit ies: Geodes



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The Effect of Crowding on Crystal GrowthThe Effect of Crowding on Crystal Growth




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PolymorphsPolymorphs

Polymorphs are minerals that have the same chemicalPolymorphs are minerals that have the same chemicalcomposition but a different crystal formcomposition but a different crystal form

Graphite and diamond polymorphs of carbonGraphite and diamond polymorphs of carbon Graphite forms at low temperature and pressureGraphite forms at low temperature and pressure

Diamond forms at high temperature and pressureDiamond forms at high temperature and pressure

Quartz, stishovite, and coesite are polymorphs of SiOQuartz, stishovite, and coesite are polymorphs of SiO22 Quartz forms at low to medium temperature and pressureQuartz forms at low to medium temperature and pressure

stishovite and coesite form at high pressure, such as thatstishovite and coesite form at high pressure, such as thatassociated with meteor impactsassociated with meteor impacts

Andelusite, kyanite, and sillimanite are polymorphs of AlAndelusite, kyanite, and sillimanite are polymorphs of Al22SiOSiO55 Andelusite is the low temperature low pressure polymorphAndelusite is the low temperature low pressure polymorph

Kyanite is the low temperature high pressure polymorphKyanite is the low temperature high pressure polymorph

Sill imanite is the high temperature high pressure polymorphSill imanite is the high temperature high pressure polymorph



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PseudomorphsPseudomorphs

Pseudomorphs are minerals that have the same crystal form butPseudomorphs are minerals that have the same crystal form but

a different chemical compositiona different chemical composition

Limonite forms cubic pseudomorphs after pyriteLimonite forms cubic pseudomorphs after pyrite

Quartz forms pseudomorphs after f luoriteQuartz forms pseudomorphs after fluorite


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Modul 5a - Minerals, definition & classes.pdf

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