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Minerals

Minerals. So what is a mineral? What are the characteristics of all minerals?. Do you Know?. Mineral Characteristics. 1. A mineral occurs naturally. 2. A mineral is solid. 3. A mineral has a definite chemical composition. 4. A mineral’s atoms are arranged in an orderly pattern.

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Minerals

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  1. Minerals

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

  3. Do you Know?

  4. Mineral Characteristics

  5. 1. A mineral occurs naturally.

  6. 2. A mineral is solid.

  7. 3. A mineral has a definite chemical composition.

  8. 4. A mineral’s atoms are arranged in an orderly pattern.

  9. A mineral’s physical properties are controlled by its internal arrangement of atoms regularly repeating, orderly pattern

  10. 5. A mineral is inorganic (was never alive)

  11. Minerals • A mineral is a naturally occurring, inorganic solid that has a definite chemical composition and crystal structure. In order for a substance to be called a mineral, it must have all five of the characteristics described in this definition.

  12. Inorganic • A mineral must be inorganic, or not formed from living thing or the remains of living things.

  13. Solid • A mineral is always a solid. Like all solids, a mineral has a definite volume and shape.

  14. Chemical Composition • A mineral has a definite chemical composition. A mineral may made of a single pure substance, or element, such as gold, copper or sulfur. Most minerals are made of two or more elements chemically combined to form a compound.

  15. General Facts About Minerals 2,000 + minerals have been identified • A few are “native elements” -- made of only one element, such as sulfur, gold. copper, and graphite (carbon) • Most are compounds, especially the silicate group (Si, O). • Other important groups are oxides, carbonates, and sulfides.

  16. MINERALS NATIVE ELEMENTS Gold (Au) Silver (Ag) Platinum (Pt) Diamond (C) Graphite (C) Sulfur (S) Copper (Cu) Gold Copper Silver

  17. Mineral Criteria • 1. Crystalline solid – atoms have specific arrangement or crystal structure • 2.Naturally occurring – not manufactured • 3.Have a definite chemical composition – may be a single element or combination • 4. Inorganic – minerals not made by living things (organic)

  18. MINERAL FORMATION • CRYSTALLIZE FROM MAGMA or LAVA solidification of liquid magma/lava to solid with a definite internal arrangement of atoms into a regular repeating pattern • PRECIPITATE FROM SOLUTION dissolved minerals come out of solution (water) to form solids

  19. Formation and Composition of Minerals • Many minerals come from magma, the molten rock beneath the Earth’s surface. When magma cools, mineral crystals are formed. How and where magma cools determine the size of the mineral crystals. When magma cools slowly beneath the Earth’s crust, large crystals form. When magma cools rapidly beneath the Earth’s surface, small crystals for

  20. Crystal Formation • Crystals may also form from compounds dissolved in a liquid such as water.When the liquid evaporates, or changes to a gas, it leaves behind the minerals as crystals. Halite, or rock salt, forms in this way.

  21. Most Abundant Elements • The eight most abundant elements in the Earth’s crust are oxygen, silicon, aluminum, iron, calcium, sodium, potassium and magnesium. There are about 100 common minerals formed from the eight most abundant elements.Of these 100, fewer than 20 are widely distributed and make up almost all the rocks in the Earth’s crust.

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

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

  24. Less than a dozen are common in most rocks • Quartz • Feldspar (group) • Muscovite (silver white mica) • Biotite (black mica) • Calcite • Pyroxene • Olivine • Amphibole (group) • Magnetite, limonite, and other iron oxides • Pyrite

  25. Common uses include: • Aluminum--packaging, transport, building • Beryllium--gemstones, fluorescent lights • Copper--electric cables, wires, switches • Feldspar--glass and ceramics • Iron--buildings, automobiles, magnets • Calcite--toothpaste, construction

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

  27. Give an example of two minerals which have the same chemical composition but different physical properties graphite & diamond

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

  29. Minerals are identified by their Physical Properties • Crystal Form – determines physical properties • Color • Streak • Luster – metallic, non-metallic • Hardness – Mohs Hardness Scale (1-10) • Cleavage • Fracture • Acid Test for carbonate minerals

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

  31. color Color is the most easily observed mineral property and the least useful!

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

  33. color Many minerals have a similar color.

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

  35. Some Colors of Quartz

  36. color For example, pure quartz is colorless or white, impurities can make the mineral rose, purple or pink!

  37. Color • The color of a mineral is an easily observed physical property. Color can be used to identify only those few minerals that always have their own characteristic color, such as malachite which is always green. The mineral azurite is always blue. • Many minerals come in a variety of colors. Some are colorless.Colors can also change.

  38. The Main Physical Properties Used to Identify Minerals Color a poor indicator minerals can be multiple colors many minerals are the same color

  39. luster Luster refers to the way a mineral shines in reflected light. Notice the difference between these two minerals?

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

  41. Examples of metallic luster

  42. More Examples of Metallic Luster Pyrite (FeS2) Galena (PbS) PYRITE GALENA

  43. luster 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.

  44. Example of non-metallic luster • Vitreous--quartz

  45. Example of non-metallic luster • Silky--example plagioclase feldspar

  46. Non-metallic and metallic luster – earthy hematite – metallic hematite

  47. Other terms that might be used include greasy, dull, and earthy. Can you tell which of these has an earthy luster and which has a vitreous luster? Were you Right? Vitreous Earthy

  48. Luster • The luster of a mineral describes the way a mineral reflects light from its surface. Certain minerals have a metallic luster, such as silver, copper and gold. Minerals that do not reflect light have a nonmetallic luster, and are described by terms like glassy, pearly, dull and silky.

  49. The Main Physical Properties Used to Identify Minerals Luster how light reflects off a mineral metallic non-metallic looks like a metal looks earthy, waxy, greasy or brilliant

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