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Atoms, Elements and Minerals A. Changing scales to looking at the elements of the earth and its crust (8 most common) B. Introduction to minerals that comprise rocks (11 most common) C. The silicate minerals (7) D. Other important rock-forming minerals (4) E. Mineral properties1

The crust is made of rocks > Rocks are made of minerals >

QuartzBiotiteFeldsparA. Changing Scale: Zooming in from global view to atomic scale

2Rocks are made of minerals > Minerals are made of atoms

A. Changing Scale: Zooming in from global view to atomic scale

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Atoms and ElementsNucleusProtons + Charge Has Mass, Atomic # Neutrons 0 Charge Mass same as One Proton Atomic Mass #ElectronsIn shells (2, 8, 8)- charge (balances each proton +)Very little Mass ElectronShells4IonsIncomplete electron shells tend to be filledE.g. Chlorine (Cl-)17 protons (at.# 17)17 electrons would make it neutral (no charge) with the last shell one electron short {2, 8, 7} SooooTends to grab an electron to fill the third shellMaking it a negatively charged Ion (anion)

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IonsOther Common ExamplesSodium, at.# 11 {2, 8, 1} Na+

Oxygen, at.# 8 {2,6}, O-2

Silicon, at.# 14 {2,8,4} Si+4

(Cation)OxygenSodium6

Most Common Elements of Earths Crust

Oxygen:O-2 Silicon:Si+4 Aluminum:Al+3 Iron:Fe+2 or +3 Calcium: Ca+2 Sodium: Na+1 Potassium: K+1 Magnesium: Mg+2B. Introduction to MineralsHalite (Rock Salt)Mineral mined for rock salt and table saltNa gives electron to ClOpposites attract, elements bondNaCl (Sodium Chloride)

9Intro to MineralsRepeating 3-D pattern forms a Crystalline Solid (or Crystal)Naturally occurring crystals are MineralsCrystalline structure and bonding leads to physical properties: hardness, crystal form, cleavage specific gravity (density) (pg. 38-43)

Crystal Form

3 planes of cleavage10

Silica TetrahedraThe building block of most common rock forming mineralsFour O2- in a tetrahedral configurationOne Si4+ nested in the center(4 -2) +4 = -4(SiO4)-4

11Silica Tetrahedra

The building block of most common rock forming mineralsFour O2- in a tetrahedral configurationOne Si4+ nested in the center(4 -2) +4 = -4(SiO4)-412Silica TetrahedraThe building block of most common rock forming mineralsFour O2- in a tetrahedral configurationOne Si4+ nested in the center(4 -2) +4 = -4(SiO4)-4

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Silica TetrahedraThe building block of most common rock forming mineralsFour O2- in a tetrahedral configurationOne Si4+ nested in the center(4 -2) +4 = -4(SiO4)-414

Silica TetrahedraThe building block of most common rock forming mineralsFour O2- in a tetrahedral configurationOne Si4+ nested in the center(4 -2) +4 = -4(SiO4)-415

Silica TetrahedraThe building block of most common rock forming mineralsFour O2- in a tetrahedral configurationOne Si4+ nested in the center(4 -2) +4 = -4(SiO4)-416

Silica TetrahedraThe building block of most common rock forming mineralsFour O2- in a tetrahedral configurationOne Si4+ nested in the center(4 -2) +4 = -4(SiO4)-417Silica TetrahedraThe building block of most common rock forming mineralsFour O2- in a tetrahedral configurationOne Si4+ nested in the center(4 -2) +4 = -4(SiO4)-4-418C. Silica Tetrahedra and Silicate MineralsSi and O bond in a tetrahedron shapeThe basic building block of most minerals of the crustBond with other tetrahedra and cations to form Silicate Minerals

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Naturally OccurringCrystallineSolidWith a definite chemical compositionA unique composition orA definite range of compositions Mineral Group, e.g. Olivine

Definition of Mineral20Silicate Minerals: Examples

E.g., OlivineIsolated silicate structure(SiO4)-4 + 2Fe+2Fe2SiO4 Fe Mg SiO4

Mg2SiO4(Fe,Mg) 2 SiO4 Olivine Mineral Group

Definite Range21Silicate Minerals: Examples

E.g., OlivineIsolated silicate structure bonded with Fe and/or MgMakes up much of Earths mantleFe/Mg rich2/7 = 0.29 = 29%Silica poor 1/7 = 0.14 = 14% % of all atoms(Ferromagnesian mineral)22Silicate Minerals: ExamplesE.g., Pyroxenes (Mineral Group)Single Chain Silicate structure (SiO3)-2 + Fe+2FeSiO3 (Fe,Mg) SiO3

MgSiO3(Fe,Mg) SiO3 Pyroxene Mineral Group Ferromagnesian

23Silicate Minerals: ExamplesE.g., Pyroxenes (Group of minerals)Single Chain Silicate structure bonded with Fe, Mg, Ca, and AlFound in Oceanic CrustFe/Mg/Ca rich (20%)Silica poor (