1. A Microsoft® PowerPoint® Link Tool Essentials of Physical Geology
PowerLecture
A Microsoft® PowerPoint® Link Tool
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Essentials of Physical Geology
5th Edition
Reed Wicander  | James S. Monroe
academic.cengage/com/earthsci

2. Minerals The Building Blocks of Rocks
Chapter 3
Minerals
The Building Blocks of Rocks

3. Introduction What is a mineral? A mineral is Naturally Inorganic
Crystalline solid
Characteristic physical properties
Specific chemical composition.
Gemstones – precious or semi-precious minerals or rocks used for decorative purposes
Fig. 3.1 a, p. 62 3

4. Introduction Are amber and pearls minerals?
Amber is considered a semiprecious “stone,” but it is not a mineral because it is organic and not crystalline.
Pearls, although they grow in mollusks, are minerals because they are crystalline and meet the other criteria for minerals.
Fig. 3.1 b-c, p. 62 4

5. Matter – What is It? Atoms and Elements
All matter is composed of chemical elements, which are themselves composed of atoms.
Atoms consist of a nucleus, of protons and neutrons, and electrons that circle the nucleus.
Elements are defined on the basis of the number of protons in the nucleus of an atom (i.e., the atomic number).
Another characteristic of an atom is its atomic mass, the sum of the numbers of protons and neutrons in the nucleus. 5

6. Matter – What is It?
What are the atomic number and atomic mass of an atom?
The number of protons in an atom’s nucleus determines its atomic number, whereas an atom’s atomic mass number is the total number of protons and neutrons in the nucleus.
For example, if an atom has 6 protons and 8 neutrons its atomic number and mass numbers are 6 and 14, respectively.
Fig. 3.4, p. 64 6

7. Nucleus 6 p 6 n 12C (Carbon 12) 13C (Carbon 13) 6 p 7 n 6 p 8 n
Figure 3.4: Carbon Isotopes.
Schematic representation of the isotopes of carbon. Carbon has an atomic number of 6 and an atomic mass number of 12, 13, or 14, depending on the number of neutrons in its nucleus.
Stepped Art
Fig. 3-4, p. 64

8. Matter – What is It? Bonding and Compounds
Atoms are joined to one another by forces known as bonding.
Atoms of different elements which are bonded to one another form compounds.
Fig. 3.5a, p. 65 8

9. Matter – What is It? Bonding and Compounds
Ionic Bonds - Ionic bonds transfer ions, with opposite electrical charges attracting one another
Halite is a compound formed by the bonding of sodium atoms to chlorine atoms.
Fig. 3.5, p. 65 9

10. + – electron transfer Sodium atom 11 p+ 11 e– Chlorine atom 17 p+
ion
11 p+
10 e– +
Chlorine
ion
17 p+
18 e– –
Figure 3.5: Ionic Bond to Form the Mineral Halite (NaCl).
Stepped Art
Fig. 3-5a, p. 65

11. Matter – What is It? Bonding and Compounds
Covalent Bonds - Covalent bonds atoms share electrons.
Fig. 3.6, p. 66 11

12. Matter – What is It? Bonding and Compounds Metallic Bonds
Metallic bonds result from extreme electron sharing.
Van der Waals bonds
Van der Waals bonds are an extremely weak bond without available electrons to form an attraction. 12

13. Explore the World of Minerals
Naturally Occurring Inorganic Substances
We define a mineral as naturally occurring
This excludes all synthetic substances made by man like synthetic diamonds and rubies.
The term inorganic deserves special consideration
Animal and plant matter are not minerals
Certain organisms, however, do use minerals, like calcite and quartz, to form their shells 13

14. Explore the World of Minerals
Mineral Crystals
Why is it that not all mineral specimens show well-developed crystals but all are crystalline solids?
As minerals form and grow, they may merge with one another to form a mosaic of interlocking crystalline solids that show no obvious crystals.
Nevertheless, individual minerals within this mosaic have their atoms arranged in a specific three-dimensional framework.
Fig. 3.8 a-b, p. 67 14

15. Explore the World of Minerals
Chemical Composition of Minerals
By definition native elements are made up of only one chemical element, such as gold (Ag) and diamond (C).
Most minerals are composed of two or more chemical elements, such as quartz (SiO²).
Geo-inSight 6., p. 73 15

16. Mineral Groups Recognized by Geologists
How Many Minerals Are There? Even though there are 92 naturally occurring elements, only 8 of them are very common in Earth’s crust.
Even among these 8, oxygen and silicon are by far the most common.
Most common minerals are made up of oxygen, silicon, and one or more other elements.
Fig. 3.10, p. 69 16

17. Mineral Groups Recognized by Geologists
Most of the more than 3,500 known minerals are silicates (compounds of silicon and oxygen, and other elements).
Additional common mineral groups include carbonates, oxides, sulfides, sulfates, and halides.
Table 3.1, p. 69 17

18. Mineral Groups Recognized by Geologists
Silicate Minerals
composed of the silica tetrahedra
Fig. 3.12, p. 70 18

19. Mineral Groups Recognized by Geologists
Silicate Minerals
Ferromagnesian silicates - made up of iron, magnesium, or both combined with other elements.
dark in color and dense
Fig a, p. 70
Fig a, p. 74 19

20. Mineral Groups Recognized by Geologists
Silicate Minerals
Nonferromagnesian silicates - lack iron and magnesium
light colored
Fig. 3.11, p. 70
Fig b, p. 74 20

21. Mineral Groups Recognized by Geologists
Carbonate Minerals
All carbonate minerals have the carbonate radical (CO³)-² as in calcite (CaCO³) and dolomite [CaMg(CO³)²].
Carbonate minerals are found mostly in the sedimentary rocks limestone and dolostone.
Carbonates are derived from the shells and hard parts of marine organisms or are precipitated from seawater as evaporites.
Fig. 3.11, p. 70
Fig. 3.14, p. 75 21

22. Mineral Groups Recognized by Geologists
Other Mineral Groups
Native Elements
All native elements are composed of a single element.
Gold, copper and diamonds commonly occur as native elements.
Geo-inSight 6., p. 73 22

23. Mineral Groups Recognized by Geologists
Other Mineral Groups
Sulfides
All sulfide minerals contain sulfur plus a metallic element as in galena (PbS) and pyrite (FeS²).
Sulfide minerals are found in all types of rocks. They commonly form along mid-oceanic ridges
Fig. 3.14b, p. 75
Fig. 3.15a, p. 78 23

24. Mineral Groups Recognized by Geologists
Other Mineral Groups
Sulfates
All sulfate minerals have the sulfate radical (SO4 -² ) as in gypsum (CaSO4 2H2O)
Sulfate minerals are common in deserts, forming from evaporation of water
Fig. 3.11, p. 70 24

25. Physical Properties of Minerals
Mineral composition and structure produce unique physical properties.
Color
Hardness
Cleavage
Crystal form
Specific gravity
p. 60 25

26. Physical Properties of Minerals
Luster and Color
Luster is the quality and intensity of light reflected from a mineral and is characterized as metallic or nonmetallic.
Color, in contrast, is a visual quality of minerals that results from the way they absorb or transmit light.
Fig. 3.15a, c, p. 78 26

27. Physical Properties of Minerals
Crystal Form
Crystal form is useful for the identification of minerals that typically show well-developed crystals.
For many other minerals, however, the crystals grow in proximity to form a crystalline mass, in which case other mineral properties such as luster, hardness, and cleavage must be used for identification.
Fig. 3.7, p. 67 27

28. Physical Properties of Minerals
Cleavage and Fracture
Mineral cleavage refers to the breakage or splitting of mineral crystals along one or more smooth planes determined by atomic structure.
When used with other mineral properties, cleavage can distinguish between minerals that otherwise look much the same.
Fracture refers to the irregular breakage of a mineral
Fig. 3.16, p. 79 28

29. Cleavage in one direction Micas—biotite and muscovite Cleavage in
Cleavage plane
Micas—biotite
and muscovite
Cleavage in
two directions
at right angles
Potassium
feldspars,
plagioclase
feldspars
Cleavage in
three directions
at right angles
Halite,
galena
Cleavage in
three directions,
not at right angles
Calcite,
dolomite
Cleavage in
four directions
Fluorite,
diamond
Cleavage in
six directions
Sphalerite
Stepped Art
Fig. 3-16, p. 79

30. Physical Properties of Minerals
Hardness
Mohs hardness scale
Ten minerals are used to compare the hardness between all the rest.
Table 3.2, p. 79 30

31. Physical Properties of Minerals
Specific Gravity (Density) - The specific gravity is a way to describe how heavy a mineral is.
Specific gravity is the ratio of the weight of a mineral to an equal volume of water.
For example, galena has a specific gravity of 7.58 gm/cm3. It is 7.38 times as heavy as an equal volume of water.
Fig. 3.14b-c, p. 75 31

32. Physical Properties of Minerals
Other Useful Mineral Properties
Feel - talc
Taste - halite
Magnetism - magnetite
Double refraction - calcite
React to dilute hydrochloric acid – calcite, dolomite 32

33. Rock-Forming Minerals
How do rock-forming minerals differ from accessory minerals?
A few minerals are common enough to be known as rock-forming minerals. Most of these are silicates.
Accessory minerals can be ignored in this endeavor because they are present in minor quantities.
Table 3.3, p. 80 33

34. Rock-Forming Minerals
Common rock forming minerals
Fig. 3.19, p.80 34

35. How Do Minerals Form?
As molten rock material known as magma (lava at the surface) cools, minerals begin to crystallize and grow
This determines the composition of various igneous rocks.
Fig. 3.19, p. 80 35

36. Natural Resources and Reserves
How does a resource differ from a reserve?
A resource is any solid, liquid, or gaseous substance in rocks whose profitable extraction is potentially feasible. Many resources are concentrations of economically important minerals.
A reserve is only that part of the resource base that can be extracted economically. 36

37. Natural Resources and Reserves
While the United States is dependent on imports for many mineral resources, Canada is more self-reliant.
Fig. 3.20, p. 81 37

38. Natural Resources and Reserves
What factors affect the status or a resource?
Market price is the most obvious determinate of whether a commodity is classified as a resource or reserve
Other factors include geographic location, labor costs, and developments in science and technology. 38

39. End of Chapter 3