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What are some examples of minerals you see in your daily life? What are some examples of minerals you see in your daily life? ► Graphite in your pencil.

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Presentation on theme: "What are some examples of minerals you see in your daily life? What are some examples of minerals you see in your daily life? ► Graphite in your pencil."— Presentation transcript:


2 What are some examples of minerals you see in your daily life? What are some examples of minerals you see in your daily life? ► Graphite in your pencil ► Glass windows ► Jewelry

3 So what is a mineral? What are the characteristics of all minerals?

4 Definition ► A naturally occurring, inorganic solid with specific chemical composition and a definite crystalline structure. ► Important in forming rocks (which we will learn about in next unit)


6 1. A mineral occurs naturally.

7 2. A mineral is solid (definite shape and volume).

8 3. A mineral has a definite chemical composition (element or compound).

9 4. A mineral’s atoms are arranged in an orderly pattern (crystal structure). ► Crystal---a solid in which the atoms are arranged in repeating patterns

10 5. A mineral is inorganic (was never alive). ► Is coal a mineral?

11 Of the almost 4000 known minerals, only about 30 are common. The most common are quartz,feldspar,mica, and calcite.

12 These minerals make up most of the rocks found in the Earth’s crust.

13 In fact, over 60% of the Earth’s crust is made up of the family of minerals known as feldspar!

14 Where Do Minerals Come From? ► Two ways:  1. Minerals from Cooling Magma ► Magma---molten material found beneath Earth’s surface ► Density forces magma upwards into cooler layers of the Earth, where it cools ► Compounds interact chemically to form minerals ► Type and amount of elements present determines which mineral will form ► Rate at which magma cools determines size of mineral

15 ► If magma cools slowly  large crystals form ► If magma cools quickly  small crystals form

16 ► 2. Minerals from Solutions  A given volume of water can only dissolve so much solid before it becomes saturated  A supersaturated solution (overfilled) can precipitate mineral crystals  Minerals can also form when elements dissolve in a supersaturated solution and the liquid evaporates…the elements remain behind and crystals form

17 Mineral Identification ► There are more than 3000 minerals, so we need a way to identify them!

18 To be able to identify these and other minerals, we need to look at the properties used to separate and distinguish these minerals.

19 Remember!: Rarely is a mineral identified by a single property. These properties need to be considered together to correctly identify a mineral.

20 Color is the most easily observed mineral property and the least useful! Some minerals can be found in a variety of colors.

21 Some exceptions to the color rule would be cinnabar, which is always red, and malachite, which is green.

22 Many minerals have a similar color.

23 Many minerals can turn colors due to impurities, or they can change colors in various circumstances.

24 For example, pure quartz is colorless or white, impurities can make the mineral rose, purple or pink

25 ► Mass/Volume ► Reflects weight and structure (no dependent on size or shape) ► Common measure of density is specific gravity

26 Specific gravity tells you how many times as dense as water the mineral is. Pure gold can have a specific gravity as high as 19.3

27 IDENTIFYING MINERALS (Continued) CRYSTAL FORM ► Takes Luck & Practice ► Well-formed crystals are uncommon ► Crystal Classification is somewhat subtle ► Crystals need time, heat, and space

28 The Crystal Classes

29 MAJOR MINERAL SUITES ELEMENTS Metallic:Au, Ag, Cu ► Not Al, Pb, Zn, Fe, etc. Nonmetallic: C - Diamond, Graphite ► Sulfur

30 MAJOR MINERAL SUITES SULFIDES: Dense, Usually Metallic Many Major Ores ► Pyrite FeS 2 ► Chalcopyrite CuFeS 2 ► Galena PbS ► Sphalerite ZnS 2 ► Molybdenite MoS 2

31 MAJOR MINERAL SUITES HALIDES: Usually Soft, Often Soluble ► Halite NaCl ► Fluorite CaF 2 SULFATES: Soft, Light Color ► Gypsum CaSO 4 ► Barite BaSO 4

32 MAJOR MINERAL SUITES OXIDES: Often Variable, Some Ores ► Hematite Fe 2 O 3 ► Bauxite Al(OH) 3 (a hydroxide) ► Corundum Al 2 O 3 (Ruby, Sapphire) CARBONATES: Fizz in Acid, Give off CO 2 ► Calcite CaCO 3 ► Dolomite CaMg (CO 3 ) 2

33 MOST IMPORTANT MINERAL SUITE: The Silicate Minerals ► Si + O = 75% of Crust ► Silicates make up 95% + of all Rocks ► SiO 4 : -4 charge ► Link Corner-To-Corner by Sharing Oxygen atoms

34 Luster refers to the way a mineral reflects light from its surface. Notice the difference between these two minerals?

35 The mineral on the left has a metallic luster, the one on the right, a nonmetallic luster.

36 Metallic vs. Nonmetallic ► Metallic---shiny surfaces that reflect light like the chrome trim on cars  Silver, gold, copper, galena ► Nonmetallic---do not shine (dull, pearly, waxy, silky)  Calcite, gypsum, sulfur, quartz

37 There are several terms used to describe nonmetallic luster. Examples could be vitreous, like the quartz on the left, or pearly, like the gypsum on the right.

38 Other terms that might be used include greasy, dull, and earthy. Can you tell which of these has an earthy luster?

39 ► Describes how a mineral feels ► Examples: smooth, rough, ragged, greasy, soapy, glassy

40 Streak of a mineral is the color of its powder when rubbed on an unglazed white tile.

41 The streak is often not the same color as the mineral. A minerals color may vary, but the streak rarely will!

42 ► One of the main tests used to distinguish pyrite (fool’s gold) from gold. ► Pyrite leaves a greenish-black streak and gold leaves a yellow streak.

43 The cleavage of a mineral is its tendency to split easily or to separate along flat surfaces. Cleavage can even be observed on tiny mineral grains making it a very useful property!

44 Mica is probably the best example as it splits into thin sheets. It is said to have one perfect cleavage.

45 Feldspar splits readily in two directions, always at or near right angles.

46 Calcite and galena cleave in three directions. They are said to have three good cleavages.

47 Not all minerals show cleavage. Those that don’t break along cleavage surfaces are said to have fracture.

48 The hardness of a mineral is a measure of how easily it can be scratched. Diamond is the hardest of all minerals, and talc is the softest.

49 Friedrich Mohs devised a hardness scale. In this scale, ten well known minerals are given numbers from one to ten. Lets take a look at the ten minerals used and some of the simple tests.

50 Moh’s Hardness Scale

51 Talc (left) is the softest and has a hardness of 1. A soft pencil lead will scratch talc. Gypsum is a bit harder and has a hardness of 2. A fingernail scratches gypsum.

52 Calcite (left) has a hardness of 3 and a copper penny just scratches it. Fluorite has a hardness of 4 and it can be scratched by an iron or brass nail.

53 Apatite (left) has a hardness of 5 and can be scratched by a steel knife blade. Feldspar has a hardness of 6 and it will scratch a window glass.

54 Quartz (left), with a hardness of 7, is the hardest of the common minerals. It easily scratches hard glass and steel. Topaz has a hardness of 8 and will scratch quartz.

55 Corundum (left) has a hardness of 9. Corundum will scratch topaz. Diamond with its hardness of 10 can easily scratch the rest of the minerals.

56 Malleable Magnetic Radioactive Flourescence Taste

57 Calcite is calcium carbonate, CaCO 3. If a drop of weak hydrochloric acid is placed on calcite, the acid bubbles as carbon dioxide is released.

58 Minerals that can be hammered thin or shaped are said to show these properties. Can you think of a mineral that might be shaped or hammered?

59 Gold would be a perfect example!

60 Some minerals that contain Iron, are magnetic and can be picked up by a magnet.

61 This is the state of glowing while under a ultraviolet light. Some minerals even glow once the light is turned off!

62 Some minerals, such as this uraninite, are radioactive. They give off subatomic particles.

63 Halite (rock salt) can be identified by its taste. This practice is not recommended

64 ► You sit on minerals, wear them, and even eat them! ► They are everywhere! ► Used to make computers, cars, televisions, desks, roads, buildings, jewelry, beds, paints, sports equipment, and medicines.

65 Ores ► A mineral that contains a useful substance that can be mined at a profit ► Hematite is an ore that contains the element iron ► Aluminum is found in the ore bauxite ► Titanium is found in the ore rutile

66 Mines ► Ores that are found deep in the Earth’s crust are removed by mining ► Ores near the surface are removed by open- pit mining

67 Gems ► Gems are valuable minerals that are prized for their rarity and beauty ► Rubies, emeralds, and diamonds are cut, polished, and used for jewelry ► Trace elements can make one variety of a mineral more colorful and more prized  Amethyst is the gem form of quartz  Rubies and sapphires are the gem forms of corundum

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