1. III.Atoms, Elements andMinerals

• A. Changing scales to looking at the

elementsof the earth and its crust( 8 most common )

B. Introduction tomineralsthat comprise rocks

( 11 most common )

C. Thesilicate minerals( 7 )

D.Otherimportant rock-forming minerals ( 4 )

E. Mineral properties

2. A. Changing Scale : Zooming in from global view to atomic scale Thecrustis made ofrocks > Rocksare made ofminerals> Quartz Biotite Feldspar 3. A. Changing Scale : Zooming in from global view to atomic scale Rocksare made ofminerals>Mineralsare made ofatoms 4. Atoms and Elements

Nucleus

• Protons

• • +Charge

• • Has Mass,Atomic #

• Neutrons

• • 0 Charge

• • Mass same as One Proton

• • Atomic Mass #

Electrons

• In shells (2, 8, 8)

• -charge(balances each proton +)

• Very little Mass

Electron Shells 5. Ions

Incomplete electron shells tend to be filled

E.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 }Soooo

• Tends to grab an electron to fill the third shell

• Making it anegativelychargedIon(anion)

6. Ions

Other Common Examples

• Sodium, at.# 11 {2, 8,1 }Na +

• Oxygen, at.# 8 {2, 6 },O -2

• Silicon, at.# 14{2,8,4}Si +4

(Cation) Oxygen Sodium 7. 8. Most Common Elements of Earths Crust Oxygen: O -2 Silicon: Si +4 Aluminum: Al +3 Iron: Fe +2or+3 Calcium:Ca +2 Sodium:Na +1 Potassium:K +1 Magnesium:Mg +2 9. B. Introduction to Minerals

Halite (Rock Salt)

• Mineral mined for rock salt and table salt

• Na gives electron to Cl

• Opposites attract, elements bond

• NaCl (Sodium Chloride)

10. Intro to Minerals

Repeating 3-D pattern forms a Crystalline Solid (orCrystal )

Naturally occurringcrystals areMinerals

Crystalline structure and bonding leads to physical properties:hardness, crystal form, cleavage specific gravity (density)(pg. 38-43)

Crystal Form 3 planes of cleavage 11.

Quartz Crystal

(SiO 2 )

Snow Flake(Ice Crystal) due tocrystallinestructure of H 2 O

Some Familiar Crystal Forms Fig. 2.15a 12. Silica Tetrahedra

The building block of most common rock forming minerals

• FourO 2- in a tetrahedral configuration

• OneSi 4+nested in the center

• (4 -2 )+4 = -4

• ( Si O 4 ) -4

13. Silica Tetrahedra

The building block of most common rock forming minerals

• FourO 2- in a tetrahedral configuration

• OneSi 4+nested in the center

• (4 -2 )+4 = -4

• ( Si O 4 ) -4

14. Silica Tetrahedra

The building block of most common rock forming minerals

• FourO 2- in a tetrahedral configuration

• OneSi 4+nested in the center

• (4 -2 )+4 = -4

• ( Si O 4 ) -4

15. Silica Tetrahedra

The building block of most common rock forming minerals

• FourO 2- in a tetrahedral configuration

• OneSi 4+nested in the center

• (4 -2 )+4 = -4

• ( Si O 4 ) -4

16. Silica Tetrahedra

The building block of most common rock forming minerals

• FourO 2- in a tetrahedral configuration

• OneSi 4+nested in the center

• (4 -2 )+4 = -4

• ( Si O 4 ) -4

17. Silica Tetrahedra

The building block of most common rock forming minerals

• FourO 2- in a tetrahedral configuration

• OneSi 4+nested in the center

• (4 -2 )+4 = -4

• ( Si O 4 ) -4

18. Silica Tetrahedra

The building block of most common rock forming minerals

• FourO 2- in a tetrahedral configuration

• OneSi 4+nested in the center

• (4 -2 )+4 = -4

• ( Si O 4 ) -4

19. Silica Tetrahedra

The building block of most common rock forming minerals

• FourO 2- in a tetrahedral configuration

• OneSi 4+nested in the center

• (4 -2 )+4 = -4

• ( Si O 4 ) -4

-4 20.

Naturally Occurring

Crystalline

Solid

With adefinitechemical composition

• A unique composition

• or

• A definite range of compositionsMineral Group ,e.g. Olivine

Definition of Mineral 21. C. Silica Tetrahedra and Silicate Minerals

Si and O bond in atetrahedronshape

The basic building block of most minerals of the crust

Bond with othertetrahedraand cations to formSilicate Minerals

* * 22. Silicate Minerals: Examples

E.g.,Olivine

• Isolated silicate

• structure

• (SiO 4 ) -4+ 2 Fe +2

• Fe 2 SiO 4

• Fe Mg SiO 4

• Mg 2 SiO 4

(Fe,Mg)2SiO 4OlivineMineralGroup

Definite Range 23. Silicate Minerals: Examples

E.g.,Olivine

• Isolated silicate structure

• bonded with iron and magnesium

• Makes upmuch of the mantle

• Fe/Mg rich >50%

• Silica poor