1. the stuff rocks are made of
Minerals
the stuff rocks are made of

2. Composition of Minerals
Element – substance that cannot be broken down into simpler substances by chemical or physical means.
112 are known (95 naturally occurring)

3. Composition of Minerals
Atoms – Smallest particles of matter that contain the characteristics of an element.
Atomic structure

4. Composition of Minerals
Chemical bonding – formation of a compound by combining two or more elements.
1. Ionic bonding - Atoms gain or lose outermost (valence) electrons to form ions
Example: Halite (NaCl)

5. Composition of Minerals
2. Covalent bonding
Atoms share electrons to achieve electrical neutrality
Example: Water (H2O) Silicon dioxide (SiO2)
H2O
Quartz

6. Composition of Minerals
3. Metallic bonding
Valence electrons are free to migrate among atoms
Weaker and less common than ionic or covalent bonds
Bronze Age tools
5,000 YBP

7. So, how small is an atom? Composition of Minerals
5:30

8. Unit 6 Minerals Objectives: Describe five characteristics of minerals
Describe process of mineral formation
Classify minerals (silicates, carbonates, oxides)
Use physical and chemical properties to identify minerals
Feldspar
Fluorite
Muscovite (mica)

9. Unit 6 Minerals
Mineral – a natural occurring, inorganic solid with an orderly crystalline structure and a definite chemical composition
Inorganic = not consisting or deriving from living matter

10. I. Five Characteristics of Minerals
Naturally occurring
Solid Substance
Ordered crystalline structure
Definite chemical composition
Generally considered inorganic

11. Sugar vs Salt

12. II. Rocks vs Minerals
Rocks are made of one or more mineral(s)
Most rocks occur as aggregates of several different minerals. Aggregate = minerals are joined in a way such that their individual properties are retained
Example: Granite rock = Quartz, Feldspar, Hornblende, Muscovite (mica)
Minerals are rocks, but they are made of only one type of mineral
All minerals are rocks, but not all rocks are minerals

13. II. Rocks vs Minerals How many minerals are there?
There are over 4000 known minerals
Only 100 minerals are considered common

14. III. Mineral Formation a. Crystallization from Magma
Slower cooling magma = bigger crystals
Faster cooling magma = smaller crystals
Examples: Feldspar, quartz, muscovite (mica), hornblende

15. Cueva de los Cristales (Cave of the Crystals) Mexico
10:00
10:00

16. III. Mineral Formation Halite Calcite
b. Precipitation – dissolved substances reacting to form minerals when water evaporates
Examples: Halite and Calcite
Halite
Calcite

17. III. Mineral Formation
c. Pressure and Temperature – when existing minerals are subjected to changes that might cause them to recrystallize while still solid under pressure.
Examples: talc

18. III. Mineral Formation
d. Hydrothermal Solutions – very hot mixture of water and dissolved substances
Example: Bornite (peacock ore), quartz, pyrite (iron sulfide)

19. III. Mineral Formation
d. Hydrothermal Solutions – very hot mixture of water and dissolved substances
Example: Gypsum Crystals

20. IV. Classification of Minerals
a. Silicates – silicon and oxygen combine to form a single structure
quartz SiO4

21. IV. Classification of Minerals
b. Carbonates – minerals that contain the element carbon, oxygen, and one or more other metallic elements
Calcite CaCO3

22. IV. Classification of Minerals
c. Oxides – minerals that contain oxygen and one or more other elements, usually metals
Hematite Fe2O3
Pyrolusite

23. IV. Classification of Minerals
d. Sulfates & Sulfides – minerals that contain the element sulfur
Pyrite FeS2

24. IV. Classification of Minerals
e. Halides (Halogens) – minerals containing a halogen ion and one or more other element(s)
Fluorite CaF2

25. IV. Classification of Minerals
f. Native Elements – minerals that contain only one type of element
Gold, Silver, Lead, Sulfur

26. V. Mineral Identification
a. All minerals have observable/measurable characteristics called properties

27. V. Mineral Identification
1. Color
Color is the most obvious property of a mineral
Unfortunately color is the least reliable property
- Slight impurities in a mineral can change the color

28. V. Mineral Identification
Streak
The color of the powder left behind on a white tile is the mineral's streak.

29. V. Mineral Identification
Luster
The luster of a mineral is the way its surface reflects light
There are two main categories of luster
Metallic: shines like a piece of metal
Nonmetallic: does not look like metal
Mineral of the same type may have the different luster (hematite)

30. V. Mineral Identification
Hardness
The ease or difficulty with which a mineral can be scratched
Diamonds are the hardest naturally occurring substance known
The Mohs Scale of Hardness is use to rate the hardness of minerals

31. Mohs Scale of Hardness

32. V. Mineral Identification
Cleavage Planes
Cleavage planes - when minerals break along flat, smooth, parallel surfaces (planes)

33. Cleavage Planes
Cleavage planes form when there are weaknesses between layers of atoms

34. V. Mineral Identification
Types of Cleavage
Count the number of parallel planes

35. V. Mineral Identification
Fracture
When breakage occurs on irregular surfaces

36. Special Properties Magnetism – some minerals are magnetic
Taste – some minerals have a distinctive taste
Reaction with dilute hydrochloric acid – some minerals fizz when a drop of acid is placed on them