1. Unit 3: Earth Materials
(35 Hours = 35 classes)

2. Minerals: Why care? Why should we care? Nearly all manufactured
products we use are obtained
from minerals.
aluminum: soft drink cans
graphite (carbon): our pencil lead
copper: wire for our electricity
talc: baby powder
silver & gold: our jewelry
silicon: our computer chips

3. Minerals: Why care? Why else care? Important geologic events that
affect us involves rocks and minerals.
Why else care?
volcanic eruptions
earthquakes
weathering and erosion
mountain building

4. 4. Possess an orderly internal structure
Minerals: the building
Minerals:
blocks of rocks
What is a mineral?
-> To be considered a mineral, it must:
1. Occur naturally
2. Be inorganic
3. Be a solid
4. Possess an orderly internal structure
5. Have a definite chemical composition

5. 2) contains a mixture of one or more minerals
Minerals: the building
Minerals:
blocks of rocks
What is a rock?
-> different from that of a mineral. A rock:
1) is solid
2) contains a mixture of one or more minerals
3) occurs naturally as part of our planet

6. Some rocks composed entirely of one mineral
Minerals: the building
Minerals:
blocks of rocks
Rocks and minerals
Some rocks composed entirely of one mineral
limestone (calcite)
Most rocks have more than one kind of mineral
granite
Some rocks contain non-mineral matter
coal (has organic debris)
obsidian (volcanic glassy rock -> not crystalline)

7. Minerals The composition of minerals
rock
mineral

8. The composition of minerals
Example from book:
Figure 2.2
Granite & constituent minerals

9. minerals rock mineral minerals The composition of minerals
So far we have:
minerals
rock
mineral
collection of
one or more
minerals
A collection
of one or more
types of atoms

10. How do we define Minerals? chemical composition
The composition of minerals
How do we define Minerals?
chemical composition
internal (“atomic”) structure
(~ 4000 minerals on Earth)

11. Example: mineral quartz made up of silicon (Si) & oxygen (O) atoms
Chapter 2: Matter and minerals
3. The composition of minerals
Atomic structure
Example: mineral quartz made up of silicon (Si) & oxygen (O) atoms

12. element: is a pure Chemical substance consisting of one type of atom.
Minerals
The composition of minerals
atom: the smallest particle of a chemical element that retains the chemical properties of that element.
element: is a pure Chemical substance consisting of one type of atom.

13. 112 known elements Only 92 occur naturally The composition of minerals

14. There are over 100 known elements, but
Minerals
The composition of minerals
There are over 100 known elements, but
only 8 of these make up more than 98.5%
of Earth’s crust by mass;
Oxygen (46.6%) 2) Silicon (27.7%)
3) Aluminum (8.1%) 4) Iron (5.0%)
5) Calcium (3.6%) ) Sodium (2.8%)
7) Potassium (2.6%) 8) Magnesium (2.1%)

15. Different elements are joined together to create specific minerals.
The composition of minerals
Different elements are joined together to create specific minerals.
Example: Quartz contains
silicon (Si) and
oxygen (O)
element
name
symbol

16. An atom is a world unto itself, and has the following parts:
Minerals
The composition of minerals
But what is an atom??
An atom is a world unto itself, and has the following parts:
nucleus: heavy central region
electrons: negatively charged particles circling nucleus
electrons
nucleus

17. protons = positive electrical charge
Minerals
The composition of minerals
protons = positive electrical charge
neutrons = neutral electrical charge
The electrons are negatively charged
neutrons
electrons
one
atom
protons

18. A model of a single atom The composition of minerals Minerals
T&L: Figure 2.4 A

19. ...in 3D The composition of minerals Minerals Again, a model
of one atom
Nucleus of protons
and neutrons
T&L: Figure 2.4 B

20. # protons determines type of atom
Minerals
The composition of minerals
# protons determines type of atom
# protons determines the atomic number
Example: All Helium atoms have 2 protons
“ Carbon “ “ “
“ Uranium “ “ “

21. The composition of minerals
Atomic structure
Minerals
The composition of minerals
Periodic table of the elements
6 => 6 protons
equals # of protons

22. Different elements combine to make compounds
Minerals
The composition of minerals
Different elements combine to make compounds
Compound- two or more elements combined.
Example 1: water (2 hydrogen atoms + 1 oxygen atom = H2O)
Example 2: salt (1 sodium atom + 1 chlorine atom = NaCl)
The smallest amount of a compound is a molecule.

23. 6 protons = carbon Carbon: The composition of minerals
# of protons determines the type of atom
6 protons = carbon
# neutrons in an atom can vary
# neutrons + # protons = “mass number”
6 protons & 6 neutrons: mass number = C
6 protons & 7 neutrons: mass number = C
6 protons & 8 neutrons: mass number = C
How we write it
Carbon: 12 13 14

24. C These variations of the same element are isotopes
Minerals
The composition of minerals
These variations of the same element are isotopes
Some isotopes are unstable, and disintegrate through radioactive decay C 14
Example: Carbon-14
is unstable
The rate of disintegration is steady, which lets us use this as a clock

25. How do different atoms combine? Bonding
Minerals
The composition of minerals
Bonding
How do different atoms combine? Bonding
3 main types of bonds:
“ionic bond” – lose or gain electrons to form ions
“covalent bond” - sharing electrons
“metallic bond” - electrons are free to move about from atom to atom

26. Minerals
The composition of minerals
When atoms give away or gain electrons, they are no longer electrically neutral: they “have a charge”
Any atom with a charge is called an “ion”
90% of minerals are ionic

27. Ionic Bonding Example: Table Salt: Sodium (Na) and Chlorine (Cl)
Minerals
The composition of minerals
Ionic Bonding
Example: Table Salt: Sodium (Na) and Chlorine (Cl)
Sodium loses an electron
to share with Chlorine atom
Now, becomes a positively
charged ion
Chlorine gains the electron
from the Sodium atom
Now, becomes a negatively
charged ion

28. Example: Sodium (Na) and Chlorine (Cl)
Minerals
The composition of minerals
Example: Sodium (Na) and Chlorine (Cl)
Atoms arrange in orderly fashion: w/ alternating sodium and chlorine
atoms, so each negative ion is surrounded by positive ions, and visa versa.

29. Example: Sodium (Na) and Chlorine (Cl)
Minerals
Example: Sodium (Na) and Chlorine (Cl)
Such orderly arrangement at the atomic level produces specific shapes
in crystals at the macroscopic level that reflect the atomic structure

30. Covalent Bonding - electron sharing Like diamond, C
Minerals The composition of minerals
Covalent Bonding - electron sharing
Like diamond, C

31. Metallic Bonding - free movement of electrons between cations
Minerals
The composition of minerals
Metallic Bonding - free movement of electrons between cations

32. ….but not all compounds are minerals: WHY?
The composition of minerals
Most minerals are compounds
….but not all compounds are minerals: WHY?

33. The structure of minerals
What determines the particular crystalline structure
of a mineral?
diamond
Amethyst
(quartz)
pyrite

34. The structure of minerals
size of the ions involved
electrical charge of the ions involved

35. Important: conditions under which a mineral forms: temperature
Minerals
The structure of minerals
Important: conditions under which a mineral forms:
temperature
pressure
Completely different minerals can form from the same atom,depending on how the atoms are arranged
more pressure -> closer packing of atoms -> different substance

36. Different minerals with the same chemical composition
The structure of minerals
Different minerals with the same chemical composition
are “polymorphs”
graphite (a form of pure carbon)
soft gray material, e.g., pencil lead
crystal structure: sheets of carbon
diamond (also pure carbon)
forms deep in Earth at high pressures,
& is hardest substance known to humans
crystal structure: dense & compact