1. Minerals The Building Blocks of Rocks

2. A Brief Introduction to Minerals
Video
A Brief Introduction to Minerals

3. Minerals - The Building Blocks of Rocks
Fluorite
Examples of minerals
Calcite
Quartz

4. Minerals - The Building Blocks of Rocks
Recall from chemistry that elements and compounds are collectively known as “substances.”
Elements bond together to form “compounds.”
Elements and compounds have a definite chemical formula.
ex.) Elements: Na is sodium and Cl is chlorine.
ex.) Compound: NaCl is sodium chloride, or common table salt.
In geology, we normally call rocky elements and compounds “minerals.”
Sodium chloride is called rock salt, or halite, when we’re discussing minerals.

5. Figure 2.2

6. Minerals - The Building Blocks of Rocks
A mineral is a naturally occurring, solid chemical substance that has a characteristic chemical composition that can be expressed by chemical symbols and formulas.
A mineral is inorganic and possesses an orderly internal structure of atoms.
By comparison, a rock, which we will study later, is a mixture of minerals and does not have a specific chemical composition.
Minerals range in composition from pure elements and simple salts to very complex silicates with thousands of known forms.
The study of minerals is called mineralogy.

7. Figure 2.3

8. Minerals
Usefulness

9. Minerals have a usefulness to living organisms.
Diamond is used for jewelry, drill bits, saw blades, and a number of other industrial uses.
Fluorite is used for the fluoride contained in toothpaste.
Talc is used to make talcum powder and baby powder.
Gypsum is used to make building materials such as drywall board (sheetrock.)

10. Minerals Criteria for Classification as Minerals

11. To be classified as a mineral, a substance must meet the following five criteria:
The substance must exist in the solid phase at room temperature.
The substance must be naturally-occurring.
The substance must be inorganic in nature.
The substance must have a fixed chemical formula.
The substance must have its atoms arranged in an orderly structure.

12. Minerals
Properties

13. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Streak
When you rub a mineral on a flat surface, the color of the powder left behind on the surface is the mineral's streak.
The streak and color of some minerals are the same. For others, the streak may be quite different from the color.

14. Although the color of a mineral may not be very helpful in identification, the streak, which is the color of the powered mineral, can be very useful.

15. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Hardness
Mineral hardness is based on the ability of one natural sample of matter to scratch another.
Diamond is the hardest known naturally occurring substance, whereas talc is the least hard.

16. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Hardness
The hardness of a material is measured against the Mohs scale by finding the hardest material that the given material can scratch, and/or the softest material that can scratch the given material.
For example, if some material is scratched by apatite but not by fluorite, its hardness on the Mohs scale would fall between 4 and 5.

17. Mohs Scale
of Hardness
Figure 2.13

18. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Cleavage
In mineral terms, cleavage describes how a crystal breaks when subject to stress on a particular plane.
If part of a crystal breaks due to stress and the broken piece retains a smooth plane or crystal shape, the mineral has cleavage.
A mineral that never produces any crystallized fragments when broken off due to stress has no cleavage.

19. Cleavage

20. Properties Result From the Mineral’s Internal Arrangement of Atoms

21. Properties of Minerals result from the minerals’ internal arrangement of atoms.
Example: Sulfur is yellow because of its internal arrangement of atoms.
Example: Quartz can appear clear or cloudy because of its internal arrangement of atoms.
Example: Halite tastes salty because of its internal arrangement of atoms.
Example: Sulfur smells bad because of its internal arrangement of atoms.

22. Properties of Minerals result from the minerals’ internal arrangement of atoms.
Example: Both diamond and graphite are made entirely of carbon atoms, but they have very different properties.
Diamond’s carbon atoms are arranged as you see here, giving it a very strong internal structure. Diamond is the hardest of the minerals.

23. Properties of Minerals result from the minerals’ internal arrangement of atoms.
Example: Both diamond and graphite are made entirely of carbon atoms, but they have very different properties.
Graphite’s carbon atoms are arranged as you see here, giving it a much weaker and softer internal structure than diamond.

24. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Habit
In mineralogy, crystal habit is the characteristic external shape of an individual crystal or crystal group. A single crystal's habit is a description of its general shape and its crystallographic forms, plus how well developed each are. Recognizing the habit may help in identifying a mineral.

25. The mineral quartz often exhibits good crystal shape
Habit

26. Pyrite (fool’s gold) has two common crystal forms
Figure 2.11

27. bladed habit
Figure 2.12A

28. prismatic habit
Figure 2.12B

29. Figure 2.12C
banded habit

30. botryoidal habit
Figure 2.12D

31. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Luster
The luster of a mineral is the way its surface reflects light. In simplest terms, minerals have a metallic or non-metallic luster. A metallic luster is a shiny, opaque appearance similar to a bright chrome bumper on an automobile. Other shiny, but somewhat translucent or transparent lusters (glassy, adamantine), along with dull, earthy, waxy, and resinous lusters, are grouped as non-metallic.

32. The freshly broken sample of galena (right) displays a metallic luster, while the sample on the left is tarnished and has a submetallic luster.

33. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Feel
The "feel" of a mineral can sometimes help identify it.
Some minerals are greasy to the touch, others are smooth, and others have a rough feel.
Diamond, which absorbs heat better than any substance, has a unique, cold feel at room temperature.
talc
greasy
fluorite
smooth
feldspar
rough

34. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Feel
Some specimens of a particular mineral may have a rough feel since they are composed of tiny, protruding crystals, while other specimens of the same mineral have a smooth texture.
Therefore, a rough feel is not necessarily an identification factor.
A greasy and smooth feel, however, are inherent to all specimens of the same mineral.
Fibrous minerals have a distinct, silky feel.

35. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Magnetism
Several minerals react when placed within a magnetic field. Some minerals are strongly attracted to the magnet, others are weakly attracted, and one mineral is repelled. There are also several minerals that are attracted to magnetic fields only when heated.
The presence of iron in a mineral is responsible for the magnetic properties of minerals in virtually all cases.

36. Video Identifying Minerals

37. 13 Rarest Gemstones and Minerals Ever Seen
Video
13 Rarest Gemstones and Minerals Ever Seen