1. Minerals
Chapter 4

2. Atomic Theory Atoms are made up of Protons, neutrons, and electrons.
Protons and neutrons are in the nucleus.
Electrons are in a cloud around the nucleus.

3. Atomic Theory
Atomic Number – tells you the number of protons in the nucleus
Always a whole number
The atomic mass tells you the number of protons AND neutrons in the atom.
Usually a decimal
The word ATOM means NEUTRAL
SO in an atom…the number of protons is the same as the number of electrons

4. Example If I have an atom that has 11 protons, the atom is sodium.
If there are 12 neutrons, the atomic mass is 23.
Since it is an atom, the number of electrons is 11.
**Electrons are not part of the atomic mass because they don’t weigh enough.**

5. You try it!
How many protons, neutrons, and electrons does an K atom have?
Answer, p= 19, n= 20, e = 19
If you have an ION, there are a different number of electrons.
If you have a positive ion, one or more electrons was lost
If you have a negative ion, one or more electrons was gained.

6. Oxygen is most abundant element
Some abundant metals
Silicon is second most abundant; aluminum is third
04.10.b1
Iron is most abundant transition metal

7. Inter- molecular force
Sharing
Loaning
Free flow
Stick together
Inter- molecular force
Metallic bond
Covalent bond
Ionic bond

8. Atoms can bond by loaning electrons
Atomic Bonding
Space for one more electron in outer shell
One electron in outer shell
Atoms can bond by loaning electrons

9. Properties of Water Molecule
Oxygen and hydrogen share electron
Water molecules are polar
Polarity helps water dissolve other compounds
+ side
- side
04.13.b

10. What is the difference between a rock and a mineral?
Minerals – Most minerals in geology consist of 2 or more elements chemically combined.
Some minerals are composed of one element.
Ex. Diamond
Rocks - a naturally formed combination of minerals.

11. What is a mineral? Solid – definite crystalline structure
Ex. Ice is a mineral, liquid water is not
Natural – Cannot be synthetic, found in nature.

12. What is a Mineral continued
Inorganic – Formed without any influence from plants or animals ie, never living
Ordered Internal Structure – Molecules occur in an organized, repeating pattern

13. What is a mineral continued…
Specific Chemical Composition – Contains atoms of chemicals in standard ratios.
Ex. Halite (table salt) –
Sodium and chlorine in equal
amounts. NaCl
Ex. Calcium carbonate – CaCO3

14. How Do We Distinguish One Mineral from Another?
5 Characteristics Used to Classify Minerals
Crystal Form
Cleavage/Fracture
Color
Luster
Microscopic Observations

15. Tests for Identifying Minerals
Hardness- resistance to being scratched by another object.
Streak- trail of broken material left on a porcelain plate
Effervescence- reaction to
diluted HCl

16. Identifying Tests Continued
Magentism- magnetic
properties
Specific Gravity – Density in relation to water. ***

17. MOHS Hardness Scale
The hardness of 10 minerals are ranked relative to one another. (p.81)

18. Crystal Shape
When growing, the outward shape of a crystal mimics the minerals internal structure.
Forms a crystalline lattice.

19. Crystal Shapes There are 6 crystal systems
Cubic system- 3 axes of equal length that intersect at 90°angles
Orthorhombic system- 3 axes of
different lengths, intersect
at 90°angles

20. Crystal Shapes
Tetragonal System- 3 axes intersect at 90° angles. 2 axes are equal in length.
Triclinic System – 3 axes intersect at oblique angles.

21. Crystal Shapes
Hexagonal System – 3 axes of equal length intersect at 60° angles. The 4th axis (vertical) can be a different length.
Monoclinic System – 3 axes, each of different length, intersect, with 2 intersections at 90° angles and the third at an oblique angle.

22. Effect of the Environment on Crystals
In order for a crystal to grow into its natural shape it must be unimpeded by surrounding material.
Minerals that grow within rocks or near other crystals are not fully formed.

23. Causes of Cleavage
Cleavage is controlled by the arrangement of atoms in a mineral and the strength of the bonds between atoms.
In order to break apart a mineral you must cleave bonds between the atoms.
The mineral breaks at the point with the weakest bonds.

24. Brown atoms bonded with blue atoms into flat sheets (strong bonds)
Sheets joined by long bonds between sheets (break along weakest bonds)

25. Fracture
When bonds all have the same strength the mineral will not break in specific areas but will break in any direction.
Mineral breaks through the lattice in nearly any direction so it will fracture

26. Types of Cleavage Cleavage can occur in multiple directions
One direction
2 perpendicular directions
2 non-perpendicular directions
3 perpendicular directions
3 non-perpendicular directions

27. Observe the number of cleavage planes in this mineral
MEDIA
0405c1_biotite.mov
INSTRUCTIONS TO STUDENTS
Observe the number of cleavage planes in this mineral
EXPLANATION
One main direction of cleavage cutting through a mineral that grew in six-sided crystals

28. Observe the number and relative orientation of cleavage planes in this mineral
MEDIA
0405c3_pyroxene.mov
INSTRUCTIONS TO STUDENTS
Observe the number and relative orientation of cleavage planes in this mineral
EXPLANATION
Two perpendicular directions of cleavage (at right angles)

29. Observe the number and relative orientation of cleavage planes in this mineral
MEDIA
0405c5_amphibole.mov
INSTRUCTIONS TO STUDENTS
Observe the number and relative orientation of cleavage planes in this mineral
EXPLANATION
Two non-perpendicular directions of cleavage (planes can intersection at angles other than 90 degrees)
04.05.c

30. Observe the number and relative orientation of cleavage planes in this mineral
MEDIA
0405c7_halite.mov
INSTRUCTIONS TO STUDENTS
Observe the number and relative orientation of cleavage planes in this mineral
EXPLANATION
Three perpendicular directions of cleavage; breaks into cubes
04.05.c

31. Observe the number and relative orientation of cleavage planes in this mineral
MEDIA
0405c9_calcite.mov
INSTRUCTIONS TO STUDENTS
Observe the number and relative orientation of cleavage planes in this mineral
EXPLANATION
Three non-perpendicular directions of cleavage; breaks into shapes like squashed boxes
04.05.c

32. Periodic Table Letters are abbreviation for element
# is atomic number (number of protons)

33. Mineral Classification
There are 7 classes of minerals
Silicates- contain oxygen and silicon
Carbonates- contain carbon and oxygen
Oxides- oxygen bonded with a metal

34. Mineral Classification Cont
Halides- contain chlorine and flourine
Sulfates- contain sulfur combined with oxygen
Sulfides- contain sulfur combined with a metal
Native minerals- contain a single element.

35. Major Classes of Rock-Forming Minerals
Oxides
Halides
Carbonates
Silicates
Sulfides
Sulfates
Native minerals