1. III. 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 properties

2. A. Changing Scale: Zooming in from global view to atomic scale
Quartz
Biotite
Feldspar
The crust is made of rocks > Rocks are made of minerals > …

3. A. Changing Scale: Zooming in from global view to atomic scale
Rocks are made of minerals > Minerals are made of atoms

4. Atoms and Elements Electron Shells Nucleus Electrons Protons Neutrons
+ 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

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 a negatively charged Ion (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
Sodium
(Cation)
Oxygen

8. Most Common Elements of Earth’s 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+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 (or Crystal)
Naturally occurring crystals are Minerals
Crystalline structure and bonding leads to physical properties: hardness, crystal form, cleavage specific gravity (density) (pg )
Crystal Form
3 planes of cleavage *

11. Some Familiar Crystal Forms
Quartz Crystal
(SiO2)
Snow Flake (Ice Crystal) due to crystalline structure of H2O
Fig. 2.15a

12. Silica Tetrahedra
The building block of most common rock forming minerals
Four O2- in a tetrahedral configuration
One Si4+ nested in the center
(4  -2) +4 = -4
(SiO4)-4

13. Silica Tetrahedra
The building block of most common rock forming minerals
Four O2- in a tetrahedral configuration
One Si4+ nested in the center
(4  -2) +4 = -4
(SiO4)-4

14. Silica Tetrahedra
The building block of most common rock forming minerals
Four O2- in a tetrahedral configuration
One Si4+ nested in the center
(4  -2) +4 = -4
(SiO4)-4

15. Silica Tetrahedra
The building block of most common rock forming minerals
Four O2- in a tetrahedral configuration
One Si4+ nested in the center
(4  -2) +4 = -4
(SiO4)-4

16. Silica Tetrahedra
The building block of most common rock forming minerals
Four O2- in a tetrahedral configuration
One Si4+ nested in the center
(4  -2) +4 = -4
(SiO4)-4

17. Silica Tetrahedra
The building block of most common rock forming minerals
Four O2- in a tetrahedral configuration
One Si4+ nested in the center
(4  -2) +4 = -4
(SiO4)-4

18. Silica Tetrahedra
The building block of most common rock forming minerals
Four O2- in a tetrahedral configuration
One Si4+ nested in the center
(4  -2) +4 = -4
(SiO4)-4

19. Silica Tetrahedra
The building block of most common rock forming minerals
Four O2- in a tetrahedral configuration
One Si4+ nested in the center
(4  -2) +4 = -4
(SiO4)-4 -4

20. Definition of Mineral Naturally Occurring Crystalline Solid
With a definite chemical composition
A unique composition or
A definite range of compositions Mineral Group, e.g. Olivine

21. C. Silica Tetrahedra and Silicate Minerals
Si and O bond in a tetrahedron shape
The basic building block of most minerals of the crust
Bond with other tetrahedra and cations to form Silicate Minerals * *

22. Silicate Minerals: Examples
E.g., Olivine
Isolated silicate
structure
(SiO4)-4 + 2×Fe+2
Fe2SiO4
Fe Mg SiO4
Mg2SiO4
(Fe,Mg) 2 SiO4  Olivine Mineral Group
Definite Range

23. Silicate Minerals: Examples
E.g., Olivine
Isolated silicate structure
bonded with iron and magnesium
Makes up much of the mantle
Fe/Mg rich >50%
Silica poor <45% *

24. Silicate Minerals: Examples
E.g., Pyroxenes (Mineral Group)
Single Chain Silicate structure
(SiO3)-2 + Fe+2
FeSiO3
(Fe,Mg) SiO3
MgSiO3
(Fe,Mg) SiO3  Pyroxene
Mineral Group
Ferromagnesian

25. Silicate Minerals: Examples
E.g., Pyroxenes (Group of minerals)
Single Chain Silicate structure
bonded with Fe, Mg, Ca, and Al
Found in Oceanic Crust
Fe/Mg/Ca rich (20%)
Silica poor (<20%)

26. Building Silicates What is the net charge of: a silica tetrahedron?
a single chain of single tetrahedra?
*Hint: a shared apex is ½ an Oxygen

27. Building Silicates What is the net charge of: a silica tetrahedron?
a single chain of single tetrahedra?
a double chain of tetrahedra?
a sheet of tetrahedra?
a framework of tetrahedra?
a framework of tetrahedra with every fourth silicon replaced with an aluminum ion?
a framework with every other Si replaced with an Al?
*Hint: a shared apex is ½ an Oxygen

28. Building Silicates What common elements would balance the charges of :
an isolated silicate?
a single chain silicate?
a double chain silicate?
a sheet silicate?
a framework silicate?
a framework of tetrahedra with every fourth silicon replaced with an aluminum ion?
a framework with every other Si replaced with an Al?

29. Silicate Minerals: Examples
E.g., Pyroxenes (Group of minerals)
Single Chain Silicate structure
bonded with Fe, Mg, Ca, and Al
Found in Oceanic Crust
Fe/Mg/Ca rich
Silica poor *

30. Single Chain Silicates
E.g., Pyroxenes (SiO3)

31. Silicate Minerals: Examples
E.g., Amphiboles (Group of minerals)
Double Chain Silicate structure
bonded with Fe, Mg, Ca, and Al
Found in Continental Crust
More silica and less iron than pyroxenes *

32. Double Chain Silicates
E.g., Amphiboles (Si8O22)

33. Silicate Minerals: Examples
E.g., Micas (Muscovite and Biotite)
Sheet Silicate structure
bonded with Al, K,
(biotite has Fe, Mg)
Found in Continental Crust
More silica and less iron than Amphiboles
E.g., Clays (Mineral Group)
Hydrated, sheet silicates from weathering of other silicates *

34. Sheet Silicates
E.g., Micas (Biotite and Muscovite) (AlSi3O10)

35. Silicate Minerals
E.g., Feldspars (Orthoclase and Plagioclase) and Quartz
Framework Silicate
bonded with Al, and K (orthoclase) or Na-Ca (plagioclase)
Found in Continental Crust
More silica than micas, no iron
Granite
Orthoclase
Quartz *

36. Framework Silicates
E.g., Quartz (SiO2) and Feldspars (AlSi3O8)

37. Framework Silicates
E.g., Quartz (SiO2) and Feldspar (AlSi3O10)