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Minerals Chapter 2Earth Materials— Minerals and Rocks 9/13.

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Presentation on theme: "Minerals Chapter 2Earth Materials— Minerals and Rocks 9/13."— Presentation transcript:

1 Minerals Chapter 2Earth Materials— Minerals and Rocks 9/13

2 Earth Materials – Minerals Minerals are the basic units that make up most of Earth’s inorganic materials Minerals have many essential uses Can you name a few?

3 What is a mineral?

4 1.It is formed naturally

5 What is a mineral? 1.It is formed naturally 2.It has a crystalline structure

6 What is a mineral? 1.It is formed naturally 2.It has a crystalline structure 3.It is solid

7 What is a mineral? 1.It is formed naturally 2.It has a crystalline structure 3.It is solid 4.It has a narrowly defined chemical composition

8 What is a mineral? 1.It is formed naturally 2.It has a crystalline structure 3.It is solid 4.It has a narrowly defined chemical composition 5.It has characteristic physical properties

9 What is a mineral? 1.It is formed naturally 2.It has a crystalline structure 3.It is solid 4.It has a narrowly defined chemical composition 5.It has characteristic physical properties 6.It is inorganic -- never living

10 Minerals Chemical composition: composed of elements Quartz – SiO2 composed of one silicon atom and two oxygen atoms Distinct Properties: color, luster, hardness, breakage, streak, taste, odor, magnetic, surface features, reactive with acid

11 Matter and Its Composition Every substance on earth is composed of “matter” Matter has mass and volume –(occupies space) solid, liquid, gas composed of elements Elements are chemical substances cannot be broken down chemically composed of atoms

12 Atoms smallest particle that retains the nature of the element Nucleus contains particles protons: + neutrons: no charge Electrons travel around the nucleus electrons: --

13 Structure of an Atom The dense nucleus of an atom –consisting of protons and neutrons –is surrounded by a cloud of orbiting electrons

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15 Particles in nucleus Atomic number: the number of protons This determines the name of the element. Atomic mass number is the number of protons + number of neutrons The number of neutrons in an atom –may vary without changing the name of the element

16 When neutrons vary Isotopes of the same element are formed Isotopes have the same atomic number Isotopes have different atomic mass numbers Isotopes of the same element behave the same chemically Isotopes are important in radiometric dating

17 Carbon Isotopes Carbon atoms (with 6 protons) –have 6 neutrons = Carbon 12 ( 12 C) –have 7 neutrons = Carbon 13 ( 13 C) –or have 8 neutrons = Carbon 14 ( 14 C) –thereby making up three isotopes of carbon.

18 Bonding and Compounds Bonding: atoms join to other atoms Compound bonding of two or more elements Oxygen gas (O 2 ) is an element Ice (H 2 O) is a compound Most minerals are compounds

19 Atomic Bonding Ionic bonds: electrons are donated or received

20 Atomic Bonding Common types of bonding among atoms to form minerals: Ionic bonds: electrons are donated or received

21 Common types of bonding among atoms to form minerals: Ionic bonds: electrons are donated or received Covalent bonds: electrons are shared Atomic Bonding

22 Common types of bonding among atoms to form minerals: Ionic bonds: electrons are donated or received Covalent bonds: electrons are shared Metallic bonds: electrons are located in a “cloud” around nucleus Atomic Bonding

23 Common types of bonding among atoms to form minerals: Ionic bonds: electrons are donated or received Covalent bonds: electrons are shared Metallic bonds: electrons are located in a “cloud” around nucleus Vanderwaals bonds: atoms are weakly attracted Atomic Bonding

24 Ionic Bonding Ion: atom that has gained or lost one or more electrons It has a negative or positive charge Ionic bonding –attraction between two ions of opposite charge Goal: atoms are more stable when outer electron shell is filled.

25 Ionic Bonding

26 halite

27 Covalent Bonding Covalent bonding –results from sharing electrons shared electrons

28 Metallic Bonding Electrons are loosely arranged in a “cloud-like” arrangement. Metals have properties of being good electrical conductors Metals are malleable

29 Minerals—The Building Blocks of Rocks Quartz: SiO 2 Ratio: 1: 2 Quartz consists of 1 silicon atom for every 2 oxygen atoms –Potassium Feldspar consists of 1 potassium, 1 aluminum, and 3 silicon for every 8 oxygen atoms KAlSi 3 O 8 1: 1: 3: 8

30 Native Elements consist of only one element. They are not compounds. gold – formula: Au diamond – formula: C

31 Allotropes of carbon “polymorphs”

32 Mineral Properties controlled by internal arrangement of atoms –Chemical composition –Crystalline structure

33 Color how reliable is color to identify a mineral? Many varieties of quartz

34 Crystal form If given enough room to grow freely –minerals form perfect crystals with –planar surfaces, called crystal faces –sharp corners –straight edges

35 Moh’s Scale of hardness arranged from 1 to 10 Hardness is a mineral’s resistance to abrasion or being scratched

36 Streak test color of a mineral in its powdered form

37 Breakage yes, they all break, but some break in predictable patterns Irregular breakage or fracture: random, smooth, round (conchoidal) with no geometric shape or parallel flat sides

38 Breakage Cleavage: tendency to break in flat surfaces that are parallel may have one, two, three, even four pairs of flat sides, or planes.

39 Types of mineral cleavage

40 Surface feature - feldspars Exsolution Lamellae Potassium Feldspar Striations Plagioclase Feldspar

41 Unique taste, odor halite and sulfur

42 Reaction with dilute hydrochloric acid – carbonate minerals

43 Common rock forming minerals

44 Rock-Forming Minerals Most rocks are solid aggregates of one or more minerals Thousands of minerals occur in rocks, but most rocks have common rock-forming minerals Most rock-forming minerals are silicates, but other groups are important

45 Silicates Silicates are minerals containing silica –Si and O They make up perhaps 95% of Earth’s crust –and account for about 1/3 of all known minerals

46 The basic building block of silicates –is the silicon oxygen tetrahedron which consists of one silicon atom surrounded by four oxygen atoms

47 Earth’s crust: elements by weight %

48 Types of Silicates Silica tetrahedra can be –isolated units bonded to other elements –arranged in chains (single or double) –arranged in sheets –arranged in complex 3D networks

49 Types of Silicates Ferromagnesian silicates (dark) –contain iron (Fe), magnesium (Mg), or both olivine, pyroxene, amphibole, biotite Nonferromagnesian silicates (light) contain potassium (K), sodium (Na), (Ca)calcium –Quartz, muscovite, feldspar

50 Ferromagnesian Silicates Common ferromagnesian silicates include Pyroxene- amphibole biotite mica olivine

51 Nonferromagnesian Silicates Quartz Potassium feldspar Plagioclase feldspar Muscovite

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53 Other Mineral Groups Carbonates contain carbonate ion CO 3 (CaCO 3 ) calcite Oxides (Fe 2 O 3 ) Magnetite Halides ( NaCl) Halite Sulfides (PbS) Galena


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