Minerals

Definition

What is a Mineral?What is a Mineral?A mineral is a naturally formed inorganic crystalline solid A mineral is a naturally formed inorganic crystalline solid with a definite chemical composition and identifying with a definite chemical composition and identifying physical propertiesphysical properties

naturally formednaturally formedformed by geologic processes in nature, not by humansformed by geologic processes in nature, not by humans

inorganicinorganicwas never alivewas never alive

crystalline solidcrystalline solida solid composed of atoms arranged in a repeating orderly a solid composed of atoms arranged in a repeating orderly frameworkframework

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

distinctive, identifying physical propertiesdistinctive, identifying physical properties

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?

Definition

• Mineral is a naturally occurring inorganic element or compound 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?

Definition

• Mineral is a structurally homogeneous solid of definite chemical composition, formed by the inorganic processes of nature.

Whitten, DGA and Brooks, JRV. 1977. The Penguin Dictionary of Geology. Middlesex: Penguin Books. p. 293.

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

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 interstitial cations may vary in different parts of the lattice

• Although strictly of “organic origin”, the constituents of many limestones, siliceous rocks, and bedded phosphate 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.

Electron-bearing shells

Model of Oxygen

Review

Review

2 protons in nucleus

10 protons in nucleusModel of Helium (He)

Model of Neon (Ne)

Model of Sodium (Na+)

Model of Chlorine (Cl-)

Review

Ionic Bonding:Electron Transfer

Review

Sodium (Na)

Sodium(Na+) ion

Chlorine(Cl ¯) ion

Chlorine (Cl)

Model of crystalline structure of Halite (salt)

Mineral Structures and AtomsReview

Model of crystalline structure

Elemental Abundances in Continental CrustElemental Abundances in Continental Crust

ELEMENT YANG MELIMPAH DI KERAK BUMI

Element Simbol % Berat % Volume % Atom

Oksigen O 46,6 93,8 60,5Silikon Si 27,7 0,9 20,5Aluminium Al 8,1 0,8 6,2Besi Fe 5,0 0,5 1,9Kalsium Ca 3,6 1,0 1,9Sodium Na 2,8 1,2 2,5Potasium K 2,6 1,5 1,8Magnesium Mg 2,1 0,3 1,4Semua elemwnt lain 1,5 - 3,3

Mineral ClassesMineral Classes

Silicate Mineral GroupSilicate Mineral Group

NonNon--silicate Mineral silicate Mineral Group Group

Silicate Mineral GroupsSilicate minerals (silicates) are composed of silica tetrahedra (SiO4

4-)For silica tetrahedra to be stable, they must either:

be balanced by positive ions,share oxygens with adjacent silica tetrahedra, orsubstitute one or more Al 3+ for Si 4+

Compositions of the silicatesMafic composition

Is rich in magnesium, iron, and/or calciumIntermediate composition

Is compositionally between mafic and felsicIs 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

Silicate Mineral Groups

The Silica TetrahedronThe Silica Tetrahedron(composed of 4 oxygen atoms surrounding 1 silicon atom)(composed of 4 oxygen atoms surrounding 1 silicon atom)

Silicate Mineral Groups

Two Two IllustrationsIllustrations

of theof theSiSi––OO44

TetrahedronTetrahedron

Single Island SilicatesSingle Island Silicates(ex.: olivine)(ex.: olivine)

Single Chain SilicatesSingle Chain Silicates(ex.: augite pyroxene)(ex.: augite pyroxene)

Silicate Mineral Groups

Silicate Mineral Groups

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

Silicate Mineral Groups

Double Chain Silicates: The Amphiboles Double Chain Silicates: The Amphiboles (e.g., hornblende)(e.g., hornblende)

Sheet Silicates: The Micas Sheet 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: (potassium feldspar, sodium and calcium plagioclase feldspar, qu(potassium feldspar, sodium and calcium plagioclase feldspar, quartz)artz)

Silicate Mineral Groups

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

Silicate Mineral Groups

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), Fe33OO4 4 (magnetite), Al(magnetite), Al22OO33 (corundum) (corundum) CarbonatesCarbonates: contain CO: contain CO3 3

22--

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 SO4 4

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), CaF2 2 (fluorite)(fluorite)

Non-silicate Mineral Groups

Non-silicate Mineral Groups

Native CopperNative Copper

How do minerals form?By crystallization from magma (molten rock material) By crystallization from magma (molten rock material)

a saturation responsea saturation responseBy crystallization (precipitation) from aqueous fluids By crystallization (precipitation) from aqueous fluids

a saturation responsea saturation responseBy chemical reaction with By chemical reaction with

magmatic fluidsmagmatic fluidshydrothermal fluidshydrothermal fluidswater during weatheringwater during weathering

By solid state transformations (metamorphism)By solid state transformations (metamorphism)changes crystal formchanges crystal formmoves ions to new locationsmoves ions to new locationspromotes 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

How do minerals form?

Crystallization of Minerals in Cavities: GeodesCrystallization of Minerals in Cavities: Geodes

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

How do minerals form?

How do minerals form?

PolymorphsPolymorphs

Polymorphs are minerals that have the same chemical Polymorphs are minerals that have the same chemical composition but a different crystal formcomposition but a different crystal formGraphite and diamond polymorphs of carbonGraphite and diamond polymorphs of carbon

Graphite forms at low temperature and pressure Graphite forms at low temperature and pressure Diamond forms at high temperature and pressure Diamond 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 pressurestishovite and coesite form at high pressure, such as that stishovite and coesite form at high pressure, such as that associated 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 polymorphKyanite is the low temperature high pressure polymorphKyanite is the low temperature high pressure polymorphSillimanite is the high temperature high pressure polymorphSillimanite is the high temperature high pressure polymorph

How do minerals form?

PseudomorphsPseudomorphs

Pseudomorphs are minerals that have the same crystal form but Pseudomorphs 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 pyriteQuartz forms pseudomorphs after fluoriteQuartz forms pseudomorphs after fluorite