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Minerals

Minerals. Building Blocks of Matter. An element is a substance that cannot be broken down into simpler substances by chemical or physical means The basic unit of matter is the atom (smallest particle of matter that retains characteristics of an element)

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Minerals

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  1. Minerals

  2. Building Blocks of Matter • An element is a substance that cannot be broken down into simpler substances by chemical or physical means • The basic unit of matter is the atom (smallest particle of matter that retains characteristics of an element) • Atoms are made of subatomic particles: protons (+), electrons (-), and neutrons • Protons (atomic number) and neutrons reside in the nucleus • Electrons move around in energy levels outside of the nucleus

  3. Building Blocks of Matter

  4. Building Blocks of Matter • Atoms of the same element but with different neutrons are isotopes • Carbon-12, Carbon-13, Radioactive Carbon-14

  5. Building Blocks of Matter • Two or more elements can combine to form compounds (H2O) • Properties of compound differ from the elements • Ionic bonds form between positive and negative ions (element loses or gains electron) • Covalent bonds involve sharing of electrons between elements (H2O) • Metallic bonds form when electrons are shared by metal ions

  6. Building Blocks of Matter

  7. Minerals • Mineral is a naturally occurring, inorganic solid, with an orderly crystalline structure and a definite chemical composition • Natural, not man-made (synthetic) • Solid at normal Earth temperatures • Crystalline- atoms or ions are arranged in orderly repetitive manner • Consistent element (gold) or chemical compound (quartz [SiO2]) • Inorganic

  8. How Minerals Form • Crystallization from magma as it cools • Precipitation occurs when water evaporates leaving the dissolved substances can react to form minerals • Changes in pressure and temperature can cause atoms to rearrange • Hydrothermal solution (water and dissolved substances between 100C-300C) form new mineral when come in contact with mineral

  9. Mineral Groups • Minerals are classified based on their composition • Silicates are composed primarily of silicon and oxygen • Make up 95% of all minerals on Earth • Ferromagnesian minerals contain a lot of the elements iron and magnesium (usually dark in color) • Nonferromagnesium silicates are usually light in color because they don’t contain iron and magnesium

  10. Mineral Groups • Sulfides have compounds combined with sulfur • Galena (PbS), sphalerite (ZnS) • Carbonates have compounds made up of a carbon atom and bordered by oxygen • Halides contain elements that combine with halogen ion (chlorine, fluorine, bromine, iodine) • Salt is a halide mineral called halite

  11. Mineral Groups • Sulfates contain compounds made of sulfur enclosed by four oxygen atoms (CaSO4) • Oxides contain element combined with oxygen • Hematite (rust) • Native elements are elements in relatively pure form • Gold (Au), Copper (Cu)

  12. Properties of Minerals • Mineral’s properties can help identify them • Hardness is a mineral’s resistance to scratching • Moh’s hardness scale ranges from 1-10 • 10 is diamond, talc is 1

  13. Cleavage • Cleavage is the breakage along planes of weakness (based on atomic arrangements) • One direction: mica breaks into sheets because bond holding sheets together is weak • Two directions: feldspar breaks into two directions at about 90 degrees • Three directions: calcite, 75 degrees

  14. Fracture and Streak • Fracture occurs when minerals don’t show cleavage when broken • Break along curved surfaces, splinter, or just break unevenly • Streak is the color of the mineral in its powdered form • Created by rubbing mineral across streak plate • More reliable than color of mineral (small amounts of different elements can change color of mineral)

  15. Color • Sapphires have different colors based on small amounts of different elements

  16. Luster and Crystal Form • Luster describes how light is reflected from the surface of a mineral • Metallic luster- have metallic appearance • Glassy- quartz; earthy- chalk • Crystal form is the visible expression of a mineral’s internal arrangement of atoms • If allowed to form slowly and without space restrictions they form consistent crystal shape

  17. Density and Acid Test • Density is the ratio of an object’s mass to its volume (D=m/V) • Density of a pure mineral is a constant value • Adding dilute HCl to an unknown mineral is the acid test • If the sample fizzes, it is a carbonate • The fizz is carbon dioxide

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