1. Minerals and Rocks
What is a mineral?

2. Minerals and Rocks A rock is – Minerals are inorganic, meaning -
Geologists don’t classify coal as a mineral-
Materials like brick and concrete -

3. Minerals and Rocks Each mineral is -
For most minerals, the proportion of elements can vary slightly while the mineral still retains a similar set of characteristics.
Within each mineral crystal, the chemical composition is nearly constant.

4. Minerals and Rocks Minerals are -
Only a fraction of the nearly 4000 known minerals are common. These common minerals are called the rock-forming minerals.
Each particle within a rock is a separate mineral crystal.
A crystal is a solid in which atoms are arranged in a regular repeating pattern.

5. Minerals and Rocks
This portrait of Abraham Lincoln on Mt. Rushmore in South Dakota was sculpted in -

6. Minerals and Rocks Granite is -
A magnified view reveals the individual crystals of the minerals that make up granite.
Feldspar
Mica
Quartz
Hornblende

7. The Properties of Minerals
What are some important properties of minerals?

8. The Properties of Minerals
Quartz that is -

9. The Properties of Minerals
Color
Some minerals can be identified -
Pyrite, also known as fool’s gold, is always golden in color.
Crystals of pure sulfur are always yellow.
But a mineral’s color can often be deceptive, because slight changes in composition can cause significant changes in a mineral’s color.

10. The Properties of Minerals
Streak
The color of a mineral’s powder is -
A mineral’s streak can be found by scraping the mineral on a piece of unglazed porcelain called a streak plate.
The color of a mineral’s streak is not always the same as the color of the mineral itself.

11. The Properties of Minerals
Although this piece of hematite is -

12. The Properties of Minerals
Luster
Luster is -
A rough, crumbly surface is said to be an earthy luster. Other terms that describe luster include silky, pearly, and vitreous (glassy.)
Galena and pyrite have a metallic luster.
Sulfur has a resinous-to-greasy luster.

13. The Properties of Minerals
Density
The density of a mineral -
In general, minerals made up of elements with higher atomic masses have higher densities than minerals made up of atoms with lower atomic masses.

14. The Properties of Minerals
Galena contains much lead, which has a relatively high atomic mass of 207. Galena’s density is -
Quartz is made up of silicon and oxygen, which have relatively low atomic masses of 28 and 16 respectively. Quartz’s density is-

15. Density of Minerals
The density of minerals varies, depending on what elements the minerals contain. Samples of the minerals in the data table were analyzed -

16. Density of Minerals
Using Tables Which mineral has the lowest density? The highest density?

17. Density of Minerals
Using Tables Which minerals have the lowest percentage of silicon and oxygen? Which has the highest?

18. Density of Minerals
Formulating Hypotheses Olivine and augite are abundant in oceanic crust and in the mantle. Quartz, muscovite, and hornblende are abundant in continental crust. Formulate a hypothesis to explain why continental crust floats higher on the mantle than oceanic crust.

19. Density of Minerals
Drawing Conclusions How is a mineral’s density related to its silicon and oxygen content?

20. The Properties of Minerals
Hardness
The atoms of minerals are held together by chemical bonds of different kinds and strengths.
Hardness is -

21. The Properties of Minerals
Hardness
A hard mineral can scratch a softer mineral.
The hardness of minerals is ranked on a scale from 1 to 10, called Mohs hardness scale.
Diamond is -
Talc is -

22. The Properties of Minerals
Geologists use scratch tests to determine the hardness of mineral specimens.
A glass plate has a hardness of 5.5. A mineral that scratches the plate has a hardness -
A copper penny, which has a hardness of about 3.5, -
A fingernail, with a hardness of 2.5, and a streak plate,-.

23. The Properties of Minerals
Fracture and Cleavage
The fracture of a mineral is -
Fracture is -

24. The Properties of Minerals
Cleavage is -
Mica and graphite form sheets. Each sheet contains chemical bonds that are very strong.
The sheets are held together with weak bonds, so they can easily be peeled apart from each other.

25. The Properties of Minerals
Mica forms -

26. The Properties of Minerals
Other Properties
Some minerals have unusual properties.
Acids dissolve -
Magnetite is -
Fluorescent minerals like fluorite give -

27. The Properties of Minerals
Some minerals have unusual electrical properties.
Quartz and tourmaline, for example, become electrically -
Quartz’s electrical properties have applications -

28. Assessment Questions
Which of the following properties would not be used to identify an unknown mineral?
crystal shape
density
hardness
size