1. Minerals: Building Blocks of Rocks Chapter 2
Earth Science, 12e
Minerals: Building Blocks of Rocks Chapter 2

2. Minerals: the building blocks of rocks
Definition of a mineral
Natural
Inorganic
Solid
Possess an orderly internal structure of atoms
Have a definite chemical composition
Mineraloid – lacks an orderly internal structure

3. Composition and structure of minerals
Elements
Basic building blocks of minerals
Over 100 are known
Atoms
Smallest particles of matter
Have all the characteristics of an element

4. Periodic Table of the Elements
Figure 2.4

5. How atoms are constructed
Nucleus – central part of an atom that contains
Protons – positive electrical charges
Neutrons – neutral electrical charges
Energy levels, or shells
Surround nucleus
Contain electrons – negative electrical charges

6. Simplified view of the atom
Figure 2.5

7. How atoms are constructed
Atomic number is the number of protons in an atom’s nucleus
Bonding of atoms
Forms a compound with two or more elements
Ions are atoms that gain or lose electrons
Isotopes
Have varying number of neutrons

8. How atoms are constructed
Isotopes
Have different mass numbers – the sum of the neutrons plus protons
Many isotopes are radioactive and emit energy and particles

9. Minerals Physical properties of minerals Habit Luster Color Streak
Hardness
Cleavage

10. The mineral quartz often exhibits good crystal shape
Figure 2.21

11. Pyrite (fool’s gold) displays metallic luster
Figure 2.11

12. Mohs scale
of hardness
Figure 2.13

13. Three examples of cleavage –halite, calcite, and fluorite
Figure 2.15 B

14. Minerals Physical properties of minerals Fracture Specific gravity
Other properties
Taste
Smell
Elasticity
Malleability

15. Conchoidal fracture
Figure 2.16

16. Minerals Physical properties of minerals Other properties Feel
Magnetism
Double refraction
Reaction to hydrochloric acid

17. Minerals A few dozen minerals are called the rock-forming minerals
The eight elements that compose most rock-forming minerals are oxygen (O), silicon (Si), aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), potassium (K), and magnesium (Mg)
Most abundant atoms in Earth’s crust are oxygen (46.6% by weight) and silicon (27.7% by weight)

18. Composition of continental crust
Figure 2.19

19. Minerals Mineral groups Rock-forming silicates
Most common mineral group
Contain the silicon-oxygen tetrahedron (molecule)
Four oxygen atoms surrounding a much smaller silicon atom
Combines with other atoms to form the various silicate structures

20. The silicate (SiO4)4– molecule
Figure 2.20

21. Minerals Mineral groups Rock-forming silicates
Groups based on tetrahedral arrangement
Olivine – independent tetrahedra
Pyroxene group – tetrahedra are arranged in chains
Amphibole group – tetrahedra are arranged in double chains

22. Hornblende – a member of the amphibole group
Figure 2.21

23. Minerals Mineral groups Rock-forming silicates
Groups based on tetrahedral arrangement
Micas – tetrahedra are arranged in sheets
Two types of mica are biotite (dark) and muscovite (light)
Feldspars – Three-dimensional network of tetrahedra

24. Minerals Mineral groups Rock-forming silicates
Groups based on tetrahedral arrangement
Feldspars
Two types of feldspar are Orthoclase and Plagioclase
Quartz – three-dimensional network of tetrahedra

25. Potassium feldspar
Figure 2.21

26. Minerals Mineral groups Rock-forming silicates Nonsilicate minerals
Feldspars are the most plentiful mineral group
Crystallize from molten material
Nonsilicate minerals
Major groups
Oxides
Sulfides

27. Minerals Mineral groups Nonsilicate minerals Major groups Sulfates
Carbonates
“Native” elements

28. Common nonsilicate mineral groups
Table 2.1

29. Minerals Mineral groups Nonsilicate minerals Carbonates
A major rock-forming group
Found in the rocks limestone and marble
Halite and gypsum are found in sedimentary rocks
Many have economic value

30. Minerals Mineral resources Reserves are already identified deposits
Ores are useful metallic minerals that can be mined at a profit
Economic factors may change and influence a resource

31. An underground halite (salt) mine
Figure 2.22