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MINERALS. BIG Idea:  Minerals are an integral part of daily life. –What exactly does ‘integral’ mean?

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Presentation on theme: "MINERALS. BIG Idea:  Minerals are an integral part of daily life. –What exactly does ‘integral’ mean?"— Presentation transcript:

1 MINERALS

2 BIG Idea:  Minerals are an integral part of daily life. –What exactly does ‘integral’ mean?

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4 A mineral is a…  naturally occurring,  inorganic,  solid with a definite chemical composition and structure.

5  There are over 3,000 known minerals on Earth  Fewer than 20 of these are considered “common”

6  Scientists ask FOUR (4) questions…  If the answer is YES to ALL 4, then the substance IS a mineral!

7 1. Does it occur naturally?  Is it found in nature? –Brass cannot be found in nature –Brass is a combination (man- made mixture) of zinc and copper –Brass is NOT a mineral

8 2. Is it inorganic? - Organic comes from living things - Inorganic never lived - Minerals must be INORGANIC - Coal is made of plants - it is organic and NOT a mineral

9 3. Is it a SOLID in crystalline form?  Oil is natural…but it is a liquid  Minerals must be SOLID  Why else would oil not pass the test?

10 4. Does it have a definite chemical composition?  Elements in minerals are combined in a definite amount, with a specific crystalline pattern  Why is concrete NOT a mineral?

11 Rocks vs. Minerals  Rocks are made up of minerals  Rocks can be made of one or more minerals

12 Major Rock-Forming Minerals:  Quartz  Feldspar  Calcite  Mica

13  Rock-forming minerals make up the Earth’s crust…

14  What are the most abundant elements in the Earth’s crust (by mass)?

15 Oxygen (O) - 46% and Silicon (Si) - 28%

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17 Composition of the Earth’s Crust  Minerals are composed of elements and compounds, and are classified into TWO (2) main groups (based on chemical composition): 1.Silicates  Contain silicon (Si) and oxygen (O)  96% of Earth’s crust 2.Nonsilicates  Do not contain silicon

18 Crystal Structure  The internal arrangement of atoms  Determines: –Crystal form –Breaking pattern –Hardness

19  Diamonds and Graphite are both made of carbon  What makes them look so different?

20  …the internal arrangement of atoms, and the bonds between them…

21 Diamond (a) vs. Graphite (b)

22  Do you know what we use graphite for?

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24 How can we identify minerals?  Based on their physical and chemical properties…

25 1. COLOR Why do you think color is not a good way to identify a mineral?

26 These 3 minerals are all samples of QUARTZ:

27 2. STREAK: the color of a mineral in POWDER form  More reliable than color

28 3. LUSTER: the way a mineral’s surface reflects light

29 Two (2) Types of LUSTER: A. Metallic - looks like metal

30 B. Nonmetallic - does not look like metal  Earthy (dull)  Pearly  Waxy  Glassy

31 4. HARDNESS: the ability of a mineral to resist scratching

32  Mohs Hardness Scale: assigns a number from 1 to 10  10 is the hardest (diamond)  1 is the softest (talc)  Estimate the hardness of a mineral by dragging the mineral on a piece of window glass to see if it scratches it:  --if it does, its hardness is 5.5 or greater  --if it does not, its hardness is less than 5.5

33 5. CLEAVAGE vs. FRACTURE: the way a mineral breaks  CLEAVAGE: –splitting of a mineral along lines or flat surfaces –usually creates smooth surfaces and edges with the same angle

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35  FRACTURE: –when a mineral breaks unevenly in a curved or irregular way

36 6. DENSITY (Specific Gravity)  Each mineral has small range of possible densities.  Good way to help identify minerals. M D V

37 Other Special Properties of Minerals… 1. MAGNETISM: minerals containing iron  Magnetite

38 2. DOUBLE REFRACTION: bending of light to produce a double image of objects viewed through them  Calcite

39 3. FLUORESCENCE – ability to glow under UV light 4. PHOSPHORESCENCE – ability to glow after the UV light is taken away

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41 5. SMELL

42 6. REACTION TO ACID  Calcite with HCl (hydrochloric acid)

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