1. Lecture 5
Earth Materials:
Minerals and Rocks

2. About Earth Materials
All Earth materials are composed of atoms bound together.
Minerals are composed of atoms bonded together and are the building blocks of rocks.
Rocks are composed of minerals and they record various geologic processes.

3. Minerals are the building blocks of rocks.
1. What Are Minerals?
Minerals are the building blocks of rocks.

4. What Are Minerals?
Geologists define mineral as a naturally occurring, solid, crystalline substance, usually inorganic, with a specific chemical composition.

5. Naturally occurring = found in nature
What Are Minerals?
Naturally occurring = found in nature
Solid, crystalline substance = atoms are arranged in orderly patterns
Usually inorganic = not a product of living tissue
With a specific chemical formula = unique chemical composition

6. 2. The Structure of Matter
The atom is the smallest unit of an element that retains the physical and chemical properties of that element.

7. Atomic nucleus: protons and neutrons.
2. The Structure of Matter
Atomic nucleus: protons and neutrons.
Electrons: cloud of moving particles surrounding the nucleus.
Example: the carbon atom (C)

8. The Carbon Atom
electron cloud
atomic nucleus

9. The Carbon Atom
electron cloud
atomic nucleus
carbon has 6
electrons …

10. The Carbon Atom electron cloud atomic nucleus carbon has 6 electrons …
proton (+)
neutron

11. The Carbon Atom electron cloud atomic nucleus carbon has 6 electrons…
… and a nucleus
of 6 protons …
electron (–)
proton (+)
neutron

12. The Carbon Atom electron cloud atomic nucleus Carbon has 6 electrons …
… and a nucleus
of 6 protons …
… and 6 neutrons having no charge.
electron (–)
proton (+)
neutron

13. 2. The Structure of Matter
Isotopes – atoms of the same element with equal numbers of protons but different numbers of neutrons.
Example: the carbon atom (C) typically has 6 neutrons and 6 protons (called C12), but there are also small amounts of C13 and C14.

14. Example: H + H + O = H2O Example: Na + Cl = NaCl
2. The Structure of Matter
Chemical reactions – interactions of the atoms of two or more elements in certain fixed proportions.
Example: H + H + O = H2O
Example: Na + Cl = NaCl

15. Chemical compounds that are minerals form by: electron sharing or
2. The Structure of Matter
Chemical compounds that are minerals form by:
electron sharing or
electron transfer

16. Carbon atoms in a diamond
Electron Sharing:
Carbon atoms in a diamond

17. Sodium (Na) + chlorine (Cl) =
Electron Transfer:
Sodium (Na) + chlorine (Cl) =
NaCl (halite)

18. Sodium (Na) + chlorine (Cl) =
Electron Transfer:
Sodium (Na) + chlorine (Cl) =
NaCl (halite)
Each sodium ion (circled in red)
is surrounded by 6 chloride ions
(circled in yellow), and vice versa.

19. in the proper proportion and proper arrangement
3. The Formation of Minerals
How do minerals form?
Crystallization –
atoms come together
in the proper proportion
and proper arrangement

20. Electrical charges of atomic ions Cation – positively charged
3. The Formation of Minerals
Electrical charges of atomic ions
Cation – positively charged
Anion – negatively charged
Atomic ions arrange themselves according to charge and size.

21. 3. The Formation of Minerals
The forces of electrical attraction between protons (+) and electrons (-) that hold minerals and other chemical compounds together
covalent bonds
ionic bonds
metallic bonds

22. 3. The Formation of Minerals

23. During cooling of molten rock During evaporation of water
3. The Formation of Minerals
When do minerals form?
During cooling of molten rock
During evaporation of water
Upon changes in temperature and pressure on existing minerals

24. Chemical classes of minerals:
4. Classes of Rock-Forming Minerals
Chemical classes of minerals:
Silicates – contain O and Si
Carbonates – contain C and O
Oxides – contain O and metallic cations
Sulfides – contain S and metallic cations
Sulfates – contain SO4 and metallic cations

25. Chemical classes (cont.): Halides – contain Cl, F, I, or Br
4. Classes of Rock-Forming Minerals
Chemical classes (cont.):
Halides – contain Cl, F, I, or Br
Hydroxides – contain OH
Native elements – masses of all the same element metallically bonded

26. 4. Classes of Rock-Forming Minerals
Formation of silicate minerals
Silicate ion (SiO44–)
Oxygen and Silicon are the two most abundant elements in Earth crust
Silicates are the most common mineral in the Earth’s crust
Oxygen ions
(O2–)
Silicon ion
(Si4+)

27. Identity is determined by: texture composition
6. What Are Rocks?
Rocks are naturally occurring solid aggregates of minerals, or in some cases, non-mineral solid matter.
Identity is determined by:
texture
composition

28. Rocks are classified into three groups:
6. What Are Rocks?
Rocks are classified into three groups:
Igneous
Sedimentary
Metamorphic

29. 6. What Are Rocks?
[granite and gneiss: John Grotzinger/Ramón Rivera-Moret/Harvard Mineralogical Museum; sandstone: John Grotzinger/Ramón Rivera-Moret/MIT.]
Production of igneous and metamorphic rocks typically requires proximity to a plate boundary

30. Igneous Rocks

31. Sedimentary Rocks

32. Metamorphic Rocks
Recrystallization of existing rocks leads to the formation of metamorphic rocks

33. Interactions between the plate tectonic and climate systems
7. The Rock Cycle
Interactions between the plate tectonic and climate systems

34. 7. The Rock Cycle

35. 7. The Rock Cycle

36. 7. The Rock Cycle

37. 7. The Rock Cycle

38. 7. The Rock Cycle

39. 7. The Rock Cycle