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Minerals of Earth’s Crust

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Presentation on theme: "Minerals of Earth’s Crust"— Presentation transcript:

1 Minerals of Earth’s Crust
Chapter 3 Earth Science Chapter 3

2 Mineral A naturally occurring, inorganic solid that has a crystal structure and a definite chemical composition. Earth Science Chapter 3

3 Mineral Must occur naturally Formed by processes in natural world
Not manufactured (made by man) Earth Science Chapter 3

4 Mineral Must be inorganic Nonexample: coal
Not made of living things or the remains of living things Nonexample: coal Comes from the remains of plants and animals Earth Science Chapter 3

5 Mineral Must be a solid Definite (unchanging) shape and definite volume Particles are tightly packed Earth Science Chapter 3

6 Mineral Must have a crystal structure
Has flat sides that meet at sharp edges and corners Atoms arranged in regular, repeating pattern Earth Science Chapter 3

7 Mineral Must have a definite chemical composition
Always contains certain elements in the same proportions Example: Quartz has one atom of silicon for every two atoms of oxygen Pure, solid elements (mostly metals) are also minerals Earth Science Chapter 3

8 Physical properties of minerals
Result of chemical composition and crystalline structure Useful for identifying minerals Many can be seen with the eye Others need tests and special equipment Earth Science Chapter 3

9 Color Easy to observe Not very useful Many have similar colors
Small amounts of impurities can dramatically change colors Ruby and sapphire are both types of corundum Weathered surfaces may hide color Earth Science Chapter 3

10 Streak Color of mineral in powdered form More reliable than just color
Tested by rubbing across a streak plate of unglazed ceramic tile Streak color may be different than mineral color Even though the color of a mineral may vary, its streak color is always the same Minerals that are harder than streak plate leave no streak Earth Science Chapter 3

11 Luster Light that is reflected from a mineral’s surface
Metallic – like polished metal Or nonmetallic Glassy Waxy Greasy Pearly Submetallic or dull Silky Earthy Earth Science Chapter 3

12 Discuss Define “mineral” in your own words.
Amber is a precious material used in jewelry. It forms when the resin of pine trees hardens into stone. Is amber a mineral? Explain. What does the phrase “definite chemical composition” mean? Earth Science Chapter 3

13 Density The amount of mass in a given space Mass per unit volume
You can compare the densities of two minerals by lifting two samples that are the same size and seeing which is heavier Calculate density by taking mass divided by volume Depends on the kinds of atoms in a mineral and how closely they are packed. Earth Science Chapter 3

14 Hardness Measure of the ability to resist scratching
Determined by the strength of the bonds between atoms Earth Science Chapter 3

15 Mohs Hardness Scale Standard scale for mineral hardness
To test an unknown mineral you must determine the hardest mineral on the scale it can scratch. If neither of two minerals scratches the other, they have the same hardness Earth Science Chapter 3

16 Crystal Structure Six basic shapes
A certain mineral always has the same basic shape Earth Science Chapter 3

17 Cleavage Tendency to split along specific planes of weakness to form smooth, flat surfaces Earth Science Chapter 3

18 Fracture Tendency to break unevenly into pieces that have curved or irregular surfaces Described by how it looks when it breaks Shell-shaped fracture Hackly fracture (jagged points) Earthy fracture (crumbly) Uneven fracture (rough surface) Earth Science Chapter 3

19 Special properties Fluorescence – the ability to glow under ultraviolet light Phosphorescence – the ability to keep glowing after the ultraviolet light is turned off Chemical reactivity Earth Science Chapter 3

20 Special properties Asterism – a six-sided star appears in reflected light Earth Science Chapter 3

21 Special properties Double refraction Magnetism Radioactivity
Light bending through the mineral produces a double image Magnetism Radioactivity Unstable Decay over time releasing particles and energy Earth Science Chapter 3

22 Discuss Name eight properties that are used to identify minerals
Compare and contrast fracture and cleavage. Graphite is made of carbon atoms arranged in thin sheets. The sheets are weakly held together. Predict whether graphite will break apart with fracture or cleavage. Explain. Earth Science Chapter 3

23 Crystallization How atoms in a crystal structure get arranged in that structure Earth Science Chapter 3

24 Minerals from magma and lava
Magma – molten rock beneath Earth’s surface Lava – what magma becomes when it reaches the surface Both form crystals as they cool and solidify Earth Science Chapter 3

25 Cooling rates Magma far underground cools slowly
Large crystals, especially if undisturbed Lava and magma close to the surface cool more quickly Smaller crystals Earth Science Chapter 3

26 Minerals from solutions
Solution – one substance dissolved in another Minerals dissolved in water Crystallize when they leave the solution Earth Science Chapter 3

27 Evaporation Minerals formed at the edges of bodies of water
Minerals formed as ancient seas evaporated Earth Science Chapter 3

28 Geode Rounded hollow rock that is lined with mineral crystals
Formed when solutions of minerals seep into the rock through a crack and then the water evaporates Earth Science Chapter 3

29 Hot water solutions Hot water dissolves minerals
The solution flows through cracks in other rocks As the water cools, crystallization occurs A vein is formed Narrow channel or slab of a mineral that is different from the surrounding rock Earth Science Chapter 3

30 Discuss What is crystallization?
What factor affects the size of crystals that form as magma cools? What is a solution? What are two ways in which minerals can form from a solution? Earth Science Chapter 3

31 Gemstones Hard, colorful minerals with brilliant or glassy luster
Valuable minerals Once polished, called gems Used for decoration, mechanical parts, grinding and polishing Earth Science Chapter 3

32 Metals Not as hard as gemstones
Can be made into wires, thin sheets, hammered, and molded without breaking Conduct heat and electricity well Earth Science Chapter 3

33 Other uses Medicines Fertilizers Talc – baby powder
Gypsum – sheetrock, cement, stucco Calcite – optical instruments Quartz – glass, watches, electronics Earth Science Chapter 3

34 Ore Rock containing minerals to be mined and sold
Earth Science Chapter 3

35 Producing metals from minerals
Prospecting – searching for ore Can use magnetic field for iron, nickel, and cobalt Mining – getting ore out of ground Strip mines, pit mines, shaft mines Smelting – getting metals out of ore Use density differences to separate Additional processing Remove impurities Make alloys Solid mixtures of a metal and another element Earth Science Chapter 3

36 Discuss What are gemstones? Why are they valuable? What is an ore?
What properties of metal make them useful to humans? If you were making a machine with lots of small, moving parts that must run constantly, would you make it out of metal or gemstones? Explain. Earth Science Chapter 3

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