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MINERALS CHARACTERISITCS
- 1. Naturally occurring
- 2.Inorganic
- 3.Solid, never liquids or gases
- 4. Narrowly defined chemical compostion
- 5. Atoms are arranged in an orderly repating pattern
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ATOMS
- A. Elements are composed of Atoms
- B. Parts of an ATOM
- 1. Nucleus
- a.Protons-positive charge
- b.Neutrons-no charge
- 2. Electrons-negative charge
- a. Orbit the nucleus in energy levels or shells
- 3. Atomic number
- a. Number of protons in the nucleus
- EXAMPLE
- i.Carbon is number six on periodic table
- ii. Atoms of carbon always have 6 protons
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BONDING
- ACompounds-two or more elements bonded together in definite proportions
- B. Bodning involves the electron in the outermost energy level
- C. Types of bonds
- 1.Ionic bonding
- a.Atoms gain or lose one or more electrons
- b. Ex:Halite (NaCl)
- 2.Covalent Bonding
- a.Atoms share electrons
- b.Example-Diamond
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Mass Numbers and Isotopes
- A. Mass number
- 1.Sum of protons and neutrons in the nucleus
- 2. Isotopes
- a.Varities of same element tha thave different numbers of neutrons
- b.Example
- i.C12-6 protons, 6 neutrons
- ii.C14-6 protons, 8 neutrons
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Properties of Minerals
- A. There are about 3500 known minerals
- 1. Most minerals are compounds-composed of two or more elements bonded together
- B. Minerals have different properties due to the elements present and the way the elements are bonded together
- C. Crystal shape
- 1. The external shape of mineral crystal is a reflection of the arrangement of the elements
- 2. Crystals form when there is enough space for well shaped crystals to form
- 3.Crystal faces- flat surfaces
- 4.Quartz-crystals are six sided pillars with pyramids on the ends
- 5. Halite-cubic crystals
- 6.Calcite-rhombohderal crystals
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Luster
- 1. Appearance or quality of light reflected from the surface of a mineral
- 2. Types of luster
- A. Metallic Luster
- i.Only a limited number of minerals have metallic luster
- B.Nonmetallic luster
- i.A large number of minerals have non metallic luster, so there are different subcategories such as vitreous and earthy
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Color
- 1.Some minerals are color specific
- 2. Many minerals, such as quartz , occur in a variety of colors
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STREAK
- 1. Color of a mineral when powdered
- 2. Use a streak plate
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Hardness
- 1. How resistant a mineral is to abrasion
- 2. Mohs hardness scale
- a.Scale of relative hardness
- b.Talc-1, diamond-10
- 3. Use objects of known hardness to assess hardness of mineral
- a. fingernail-2, copper penny-3.5, glass-5.5
- 4. NOTE- ALWAYS PUT THE COPPER PENNY AND GLASS ON A SOLID SURFACE WHEN TESTING HARDNESS
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CLEAVAGE
- 1. Tendency of mineral to break along weak bonds in the atomic structure
- a. Produces flat planes on the mineral
- 2.Count the number of directions of cleavage and the angle between the cleavage planes
- a. One directioin of cleavage
- b. Two directions of cleavage
- c. Three directions of cleavage at right angles-halite
- d. Three directions of cleavage NOT at right angle-calcite
- e. four directions of cleavage
- f.Six directions of cleavage
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FRACTURE
- 1. Some minerals break unevenly
- 2.Conchoidal Fracturee
- a. Quartz breaks along smooth, curved surfaces
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Specific Gravity
- 1. The ratio of the weight of a mineral to the weight of an equal volume of water
- 2. Most minerals have SG=2.5-3.5
- 3. Some minerals have a high specific gravity and feel heavy -Galena
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Specific properties
- 1. Calcite-effervesces in HCl
- 2. Talc-feels soapy
- 3.Halite-tastes salty
- 4.Magnetite-magnetic
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Mineral Groups
- A. Most abundant elements in the Earths crust
- 1. Oxygen(O), silicon (Si), Aluminum (Al), iron (Fe), calcium (Ca), sodium (Na)
- , potassium (K), magnesium (Mg)
- B. Minerals grouped according to the elements they are composed of
- C. Silicate Group
- 1. Most abundant group of minerals
- 2. Minerals in this group all have the silicon, oxygen tetrahedron (SiO4)-4, which is a complex ion
- 3. Silicate minerals are constructed of silicon-oxygen tetrahedral joined together in silicate structures
- a. Most tetrahedra are joined by sharing oxygen atoms with neighboring tetrahedra
- 4. Silicates structure
- a. Isolated tetrahedron
- i. Linked to neighboring tetrahedral by positive ions
- b.single chains
- c. double chains
- d. sheets- micas (muscovite, biotite)
- e. Three dimensional networks-Quartz (SiO2)
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Carbonate Groupe
- 1.Minerals in this group all have (CO3)-2 complex ion
- 2.Calcite -CaCO3
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Halide Group
- 1. Minerals in this group all have halide elements such as chlorine(Cl-1)
- fluorine(F-1)
- 2. Halite-NaCl
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Oxide Group
- 1.Minerals in this group have oxygen (O-2) in their atomic structure
- 2. Hematite-Fe2O3
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Sulfates (SO4)-2
- 1.Gypsum-CaSO42H2O
- 2. Used to make wallboard
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Native Elements
- 1. Minerals that composed of only one element
- 2.Native copper, silver and gold, diamond, graphite
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