Exploring Minerals and Rocks: Nature's Hidden Treasures

1. Minerals, Rocks and Resources

2. Minerals • Natural substances that are inorganic. • The substance was not formed by or from living things such as plants or animals. • Chemical elements or compounds. • Minerals can be identified by their physical and chemical properties. • Color, Luster, Streak, Hardness, Breakage, Specific Gravity (Density), Structure, and Cleavage.

3. Luster • The way light is reflected from a cut surface of a mineral. • Metallic Luster • hard, shiny • Nonmetallic Luster • shiny, glassy, waxy, pearly, earthy (dull)

4. Streak • Rubbing a fresh corner of the mineral across a white, unglazed streak plate. • The streak is the powdered form of the mineral. • Some metallic minerals leave behind a powder that is not the same color as the mineral.

5. Crystal Structure • A regularly shaped solid formed by an ordered pattern of atoms. • Examples include: Six sided, cubic, rectangular, sheets, fibers.

6. Hardness • Minerals can be tested by scratching the unknown mineral with the edge or point of other minerals of known harness.

7. Mohs Scale of Hardness

8. Cleavage • If a mineral breaks along a flat surface, it shows cleavage (to cut, or cleave). • Many minerals break along cleavage planes, sometimes parallel to the sides of crystals. • Those that break along even surfaces that do not follow the crystal arrangement are said to fracture.

9. Density • Can be found by either dividing the mass of a sample by its volume or flotation. • Water’s density is 1 g/cm3 • A substance will sink in water if it is more dense and float if it is less dense. • Specific Gravity is a ratio of the density of a substance to the density of water.

10. Rocks • Nearly all rocks are composed of one or more minerals. • Geologists classify rocks according to how they were formed. • Igneous rocks form from lava when it reaches the surface, cools and solidifies. • Sedimentary rocks result from the compaction and cementing of layers of sediment. • Metamorphic rocks form when other types of rocks are changed by heat and/or pressure.

11. Igneous Rocks • The result of the solidification of magma or lava. • Most lack layering, however successive lava flows can form a layered rock structure. • Those that cool slowly, deep within Earth, are composed of large crystals. • Those that cool faster, at or near the Earth’s surface, have smaller or no visible crystals.

12. Igneous Rock Formation

13. Igneous Rock Classification

14. Sedimentary Rocks • Most are composed of the weathered remains of other rocks. • Usually are formed by the compression and cementing of particles of sediment. • Generally exist as a thin layer over metamorphic and igneous rocks.

15. Sedimentary Rock Characteristics • Fragmental rocks are made up of different sized particles such as shale, sandstone and conglomerate (composed of pebbles or larger stones held together by natural cement). • Organic sedimentary rock contain the accumulation of plant and animal remains. • Fossils are commonly found. • Chemical sedimentary rocks are deposited by the settling of materials from solution in seawater. • This occurs during the evaporation of seawater and when chemical reactions in the water form compounds that settle. • Rock Salt is an example.

16. Sedimentary Rock Classification

17. Metamorphic Rocks • Form when sedimentary and igneous rocks are changed by heat and/or pressure. • The only kind of rock that forms directly from another rock. • Metamorphism may cause structures, such as layering, to become distorted or to disappear. • It also may cause new minerals to form, and/or crystals to grow. • Most are formed deep within the Earth and pushed to the surface when mountains are formed.

18. Metamorphic Rock Classification • Texture • Appearance and feel of the rock surface • Grain Size • Composition • Type of Metamorphism

19. Metamorphic Rock Classification

20. The Rock Cycle • Natural changes in rocks and rock material that takes place at the Earth’s surface and within Earth. • Nearly all rocks are made from the remains of other rocks. • Rocks are classified based of their origin. • Rocks can change in response to changing conditions at the surface or within Earth.

21. The Rock Cycle

22. Natural Resources • Substances from the Earth. • Renewable resources can be replaced after they have been used. • trees, fresh water, wind • Nonrenewable resources cannot be replenished after they are used for millions of years, if at all. • Metals - gold, copper, iron, Fossil Fuels – coal, oil and natural gas

23. Alternative Energy Sources • Solar energy can be used to provide heat, hot water and generate electricity. • However, the amount of solar energy that reaches Earth varies with the time of day and the seasons. • Geothermal energy, heat from within Earth, can be used but is available only in certain areas around the world.

24. Alternative Energy Sources • Wind-driven generators are used in many areas to provide electricity where there are strong, steady winds. • Nuclear energy can generate electricity without pollution. • However, there is a danger of a nuclear accident and long-term storage of radioactive wastes.