1. Matter and Minerals

2. Matter Elements and the Periodic Table
 Elements are the basic building blocks of minerals.
 Over 100 elements are known.

3. Matter Atoms  Smallest particles of matter
 Have all the characteristics of an element
 The nucleus is the central part of an atom and contains
protons, which have positive electrical charges
neutrons, which have neutral electrical charges

4. Matter Atoms  Energy levels, or shells
surround the nucleus
contain electrons—negatively charged particles
 The atomic number is the number of protons in the nucleus of an atom.

5. Model of an Atom

6. Isotopes
Matter
 Isotopes of an element have the same number of protons but varying numbers of neutrons.
 Have different mass numbers: the sum of the neutrons plus protons
 Many isotopes are radioactive and emit energy and particles.
 The mass number is the number of neutrons and protons in the nucleus of an atom.

7. Why Atoms Bond
Matter
 When an atom’s outermost energy level does not contain the maximum number of electrons, the atom is likely to form a chemical bond with one or more atoms.
A compound consists of two or more elements that are chemically combined in specific proportions.
An ion is an atom that gains or losses electrons.

8. Matter Types of Chemical Bonds
1. Ionic bonds form between positive and negative ions.
2. Covalent bonds form when atoms share electrons.
3. Metallic bonds form when metal ions share electrons.

9. Minerals: the building blocks of rocks
Definition of a Mineral:
naturally occurring
inorganic
solid
characteristic crystalline structure
definite chemical composition

10. How do we identify minerals?
Physical properties:
Color
Luster
Hardness
Crystal shape
Cleavage
Specific gravity
Other

11. Physical Properties of Minerals
Color:
Most obvious, but often misleading
Different colors may result from impurities
Example:
Quartz

12. Physical Properties of Minerals
Color:
Streak – color of a mineral in powdered form
(used for metallic minerals)
Obtained by scratching a mineral on a piece of unglazed porcelain.
Example:
Hematite

13. Streak
Red chalk on a chalk board makes red marks. White chalk makes white marks.
Not all minerals work this way. When some minerals are scratched along a ceramic streak plate, it creates a different color.

14. Gold
When gold is run across a streak plate it makes a yellowish-gold color.
That makes sense.

15. Pyrite or “Fool’s Gold”
When pyrite is run across a streak plate, it has a black or dark green streak.
Pyrite is not worth much money, while gold is worth a lot. They look alike, so miners call it fool’s gold.

16. Hematite Hematite’s color is grey, but its streak is red.
Hema means blood.
The mineral was named hematite because it looked like it was bleeding when it was taken across a streak plate.

17. One mineral property we will not use…
COLOR

18. A mineral can be many different colors. Below is Mica.

19. Many minerals can be the same color. Below are gold colored minerals
Many minerals can be the same color. Below are gold colored minerals. Which one is gold?

20. None of them were real gold.
The answer…
None of them were real gold.

21. Just like with people…
Outside color does not tell you much about the important characteristics.

22. Physical Properties of Minerals
Luster:
How a mineral surface reflects light
Two major types:
Metallic luster
Non-metallic luster
Metallic
example:
Galena
Non-metallic
example:
Orthoclase

23. Pyrite (Fool’s Gold) Displays Metallic Luster.

24. Physical Properties of Minerals
Hardness:
How easy it is to scratch a mineral
Mohs Scale of Hardness
relative scale
consists of 10 minerals, ranked 1 (softest) to 10 (hardest)

25. Mohs Scale of Hardness Hardest (10) – Diamond Softest (1) – Talc
Common objects:
- Fingernail (2.5)
- Copper penny (3.5)
- Wire nail (4.5)
- Glass (5.5)
- Streak plate (6.5)

26. Hardness Is measured by how easy it is to scratch.
Geologists order the hardness by…
Scratched by a fingernail.
Scratched by a penny.
Scratched by a nail.
Scratched by a diamond.
These are not all of the tools geologists use, but it will work for our experiment.

27. Gypsum is soft, it can be scratched by a fingernail.

28. Calcite is soft, but a little harder because it cannot be scratched by a fingernail, but it can be scratched by a penny.

29. Fluorite is harder. It can be scratched by a nail, but not a penny or fingernail.

30. Diamonds are the hardest mineral, so it scratches every mineral.

31. Physical Properties of Minerals
Crystal shape (or form):
external expression of a mineral’s internal atomic structure
planar surfaces are called crystal faces
angles between crystal faces are constant for any particular mineral
Quartz
Pyrite

32. Physical Properties of Minerals
Cleavage vs. Fracture:
The way a mineral breaks
Cleavage: tendency of a mineral to break along planes of weakness
Minerals that do not exhibit cleavage are said to fracture
Do not confuse cleavage planes with crystal faces! Crystal faces are just on the surface and may not repeat when the mineral is broken.

33. Physical Properties of Minerals
Cleavage is described by:
Number of planes
Angles between adjacent planes
These are constant for a particular mineral

34. Physical Properties of Minerals
Cleavage (1 direction):
Example: mica

35. Mica Has Cleavage in One Direction

36. Physical Properties of Minerals
Cleavage (2 directions):
orthoclase
amphibole

37. Physical Properties of Minerals
Cleavage (3 directions):
halite
calcite

38. Physical Properties of Minerals
Cleavage (4 directions):
fluorite

39. Physical Properties of Minerals
Fracture:
minerals that do not exhibit cleavage are said to fracture
smooth, curved surfaces when minerals break in a glass-like manner: conchoidal fracture
Quartz

40. Conchoidal Fracture

41. Physical Properties of Minerals
Specific gravity:
weight of a mineral divided by weight of an equal volume of water
metallic minerals tend to have higher specific gravity than non-metallic minerals
Galena
SG=7.5
Quartz
SG=2.67

42. Physical Properties of Minerals
Other properties:
reaction with hydrochloric acid (calcite fizzes)
taste (halite tastes salty)
feel (talc feels soapy, graphite feels greasy)
magnetism (magnetite attracts a magnet)

43. Mineral Groups Rock-forming minerals
~30 common minerals make up most rocks in Earth’s crust
Composed mainly of the 8 elements that make up over 98% of the crust

44. SILICATES Mineral Groups Common cations that bond with silica anions
Element Abundances
Silica
(SiO4)4-
SILICATES
Common cations that
bond with silica anions
All others: %

45. Mineral Groups Silicates (most abundant)
Non-silicates (~8% of Earth’s crust)
Oxides O2-
Carbonates (CO3)2-
Sulfides S2-
Sulfates (SO4)2-
Halides Cl-, F-, Br-
Native elements (single elements; e.g., Au)

46. Mineral Groups Non-ferromagnesian Silicates (K, Na, Ca, Al)
Silicates (Fe, Mg)
Oxides
Carbonates
Sulfides/sulfates
Native elements

47. Mineral Groups – Silicates
Tetrahedron
fundamental building block
4 oxygen ions surrounding a much smaller silicon ion
Silicon-oxygen
tetrahedron
(SiO4)4-

48. Mineral Groups – Silicates
Joining Silicate Structures
How tetrahedra may be linked:
independent tetrahedra
single chains
double chains
sheets
3-D framework

49. Mineral Groups – Silicates –

50. Mineral Groups – Silicates
Olivine Group
dark silicates (Fe-Mg)
 ferromagnesian
No cleavage

51. Mineral Groups – Silicates
Pyroxene Group
Ferromagnesian / dark silicates (Fe-Mg)
Augite
2-directions
of cleavage
(at nearly 90 degrees)

52. Mineral Groups – Silicates
Amphibole Group
Ferromagnesian / dark silicates (Ca, Fe-Mg)
Hornblende
2-directions
of cleavage
(not at 90 degrees)

53. Mineral Groups – Silicates
Mica Group and Clay Minerals
light silicates (K, Al)
 non-ferromagnesian
Muscovite
1-direction
of cleavage

54. Mineral Groups – Silicates
Feldspar Group
light silicates (K-Na-Ca, Al)
K-feldspar
Most common mineral group
Orthoclase
Plagioclase
2-directions
of cleavage
(at 90 degrees)
Ca/Na-feldspar

55. Mineral Groups – Silicates
Quartz
light silicates (pure SiO2)
no cleavage
(conchoidal fracture)
hard, resistant to weathering
Quartz

56. Minerals Mineral Groups 2. Carbonates 3. Oxides
Minerals that contain the elements carbon, oxygen, and one or more other metallic elements
3. Oxides
Minerals that contain oxygen and one or more other elements, which are usually metals

57. Minerals Mineral Groups 4. Sulfates and Sulfides 5. Halides
Minerals that contain the element sulfur
5. Halides
Minerals that contain a halogen ion plus one or more other elements
6. Native elements
Minerals that exist in relatively pure form

58. Sulfides

59. Native Copper