Minerals PDF

Minerals MINERALS ARE MADE UP OF SINGLE ELEMENTS OR COMPOUNDS ELEMENTS A SUBSTANCE THAT CANNOT BE BROKEN DOWN TO ANY SIMPLER SUBSTANCE 8 MOST COMMON ELEMENTS IN THE EARTH’S CRUST: 1.) OXYGEN 46% 3-8.)THE REMAINING 25% IS COMPOSED OF Al, Fe,...

Minerals MINERALS ARE MADE UP OF SINGLE ELEMENTS OR COMPOUNDS ELEMENTS A SUBSTANCE THAT CANNOT BE BROKEN DOWN TO ANY SIMPLER SUBSTANCE 8 MOST COMMON ELEMENTS IN THE EARTH’S CRUST: 1.) OXYGEN 46% 3-8.)THE REMAINING 25% IS COMPOSED OF Al, Fe, Ca, Na, K, Mg 2.) SILICON 29% A. Mineral Characteristics shared by all minerals: ◼ 1. Natural – occurs naturally – NOT manmade What is a mineral? ◼ 1. Natural ◼ 2. Inorganic – Is not alive – Was never alive What is a mineral? ◼ 1. Natural ◼ 2. Inorganic ◼ 3. Crystalline – Atoms are arranged in an orderly pattern  What is a mineral? ◼ 1. Natural ◼ 2. Inorganic ◼ 3. Crystalline ◼ 4. Definite chemical composition – Chemical formula – SiO2 is Quartz  What is a mineral? ◼ 1. Natural ◼ 2. Inorganic ◼ 3. Crystalline ◼ 4. Definite chemical composition ◼ 5. Solid – Not a gas, not a liquid How will we remember this? ◼Natural ◼Inorganic ◼Crystalline ◼Definite chemical composition ◼Solid Mineral Characteristics shared by all minerals: Now I Can Define mineralS! ◼ Natural ◼ Inorganic ◼ Crystalline ◼ Definite chemical composition ◼ Solid B. Physical Properties of Minerals ◼ 1. Color – First impression – Not very reliable because a lot of minerals can occur in many different colors  COLOR LEAST USEFUL PROPERTY, CHANGE IN THE CHEMICAL FORMULA WILL VARY THE COLOR OF THE MINERAL. (QUARTZ) SiO2 ROSE QUARTZ CRYSTAL QUARTZ CONTAINS TITANIUM OXIDE AND MANGANESE OXIDE TO MAKE A ROSE COLOR  Quartz ◼ Purple Amethyst  Clear Fluorite Blue Green Purple Physical Properties of Minerals ◼ 1. Color ◼ 2. Streak – The TRUE color of a mineral – Color of a mineral’s powder Streak Minerals with a hardness greater than “7” usually don’t create a streak on the streak plate because they are harder than the Porcelain tile (unless the streak plate is specially made).  Physical Properties of Minerals ◼ 1. Color ◼ 2. Streak ◼ 3. Hardness – A mineral’s resistance to being scratched – Mohs Hardness Scale from 1-10 Hardness depends on how “tightly packed” the atoms are.  Mohs Hardness Scale 1 Talc Softest 2 Gypsum 3 Calcite 4 Fluorite 5 Apatite 6 Potassium feldspar 7 Quartz 8 Topaz 9 Corundum 10 Diamond Hardest  Physical Properties of Minerals ◼ 1. Color ◼ 2. Streak ◼ 3. Hardness ◼ 4. Cleavage – Splits along definite planes “Cleav” = to split Cleaver  BREAKAGE PATTERN CLEAVAGE- TENDENCY OF A MINERAL TO SEPARATE ALONG PLANES OF WEAKNESS ONE PLANE OF WEAKNESS BASAL CLEAVAGE (MICA) TWO PLANES OF CLEAVAGE AT 900 (ORTHOCLASE)  THREE PLANES OF WEAKNESS AT 900 = CUBIC (HALITE) THREE PLANES NOT AT 900 = RHOMBOHEDRAL (CALCITE) Physical Properties of Minerals ◼ 1. Color ◼ 2. Streak ◼ 3. Hardness ◼ 4. Cleavage ◼ 5. Fracture – Breaks irregularly, jagged edges Fracture FRACTURE- NO PLANES OF WEAKNESS SO THE MINERAL BREAKS ALONG IRREGULAR SURFACES CONCHOIDAL- SURFACES ARE SOMEWHAT ROUNDED, SHELL-LIKE (QUARTZ)  UNEVEN- ROUGH SURFACE, NO DISTINGUISHABLE PATTERN FIBROUS- JAGGED SURFACE LIKE FIBERS (WOLLASTONITE) Physical Properties of Minerals ◼ 1. Color ◼ 2. Streak ◼ 3. Hardness ◼ 4. Cleavage ◼ 5. Fracture ◼ 6. Luster – How light shines off a mineral – Metallic or Nonmetallic Luster ◼ Metallic ◼ Nonmetallic  LUSTER - THE WAY A MINERAL SHINES IN REFLECTED LIGHT. METALLIC- LOOKS LIKE METAL IN THE WAY THE MINERAL REFLECTS LIGHT GALENA PYRITE NON-METALLIC- DOES NOT LOOK LIKE POLISHED METAL, SO OTHER TERMS ARE USED VITREOUS- SHINY, GLASSLIKE (QUARTZ) PEARLY LOOKS LIKE PEARLS WHEN LIGHT IS REFLECTED OFF OF THE SURFACE (OPAL)  WAXY- DULL SHINE LIKE CANDLE WAX (SULFUR, OLIVINE) EARTHY- NO SHINE AT ALL (BAUXITE) ADAMANTINE- BRILLIANT GLOW, BEAM OF LIGHT AT A CERTAIN ANGLE (DIAMOND) Physical Properties of Minerals: Used for Identification (I.D.) ◼Color ◼Streak ◼Hardness ◼Cleavage ◼Fracture ◼Luster C. Special Properties ◼ 1. Magnetism – Attracted to a magnet – Contains IRON, cobalt, or nickel Special Properties ◼ 1. Magnetism ◼ 2. Double refraction – Looking through it, you see “double” – Ex. Calcite  Special Properties ◼ 1. Magnetism ◼ 2. Double refraction ◼ 3. Fluorescence – Glows under ultraviolet (UV) light. – Ex. Fluorite Calcite Celestite Fluorescence under ultraviolet, UV light Special Properties ◼ 1. Magnetism ◼ 2. Double refraction ◼ 3. Fluorescence ◼ 4. Phosphorescence – Continues to glow even after the UV light has been removed. – Ex. Zinc sulfide, Strontium aluminate *EFFERVESCENCE – ADDING HCL TO A MINERAL CAUSES IT TO FIZZ *TASTE – HALITE Special Properties ◼ 1. Magnetism ◼ 2. Double refraction ◼ 3. Fluorescence ◼ 4. Phosphorescence ◼ 5. Piezoelectric – Electricity is generated from Pressure – Crystals which acquire a charge when compressed, twisted or distorted – Example: Quartz Piezoelectric (Pressure=Electricity) Special Properties ◼Magnetism ◼Double refraction ◼Fluorescence ◼Phosphorescence ◼Piezoelectric  Special Properties ODOR – SOMETIMES THE POWDER OF A MINERAL HAS A CERTAIN ODOR (SULFUR SMELLS LIKE ROTTEN EGGS)  Special Properties FLUORESCENCE – THE ABILITY TO GLOW UNDER ULTRA VIOLET LIGHT (SPHALERITE) SPECIFIC GRAVITY (DENSITY) – SOME MINERALS HAVE ATOMS VERY TIGHTLY PACKED, AND FEEL HEAVIER BECAUSE THEY ARE MORE DENSE (GALENA) ◼ Minerals Based on their Chemical Properties: ◼ 1. Silicates – minerals containing 2 of the most abundant elements in the Earth’s crust, namely, silicon and oxygen. When linked together, these two elements form the silicon oxygen tetrahedron – the fundamental building block of silicate minerals. Over 90% of the rock-forming minerals belong to this group. ◼ 2. Oxides – minerals containing Oxygen anion (O2-) combined with one or more metal ions ◼ 3. Sulfates – minerals containing Sulfur and Oxygen anion (SO4)- combined with other ions ◼ 4. Sulfides – minerals containing sulfur anion (S2)- combined with one or more ions. Some sulfides are sources of economically important metals such as copper, lead and zinc. ◼ Minerals Based on their Chemical Properties: ◼ 5. Carbonates – minerals containing the carbonate anion (CO3)2- combined with other elements ◼ 6. Native Elements – minerals that form as individual elements. ◼ a. Metals and Inter-metals – minerals with high thermal and electrical ◼ conductivity, typically with metallic luster, low hardness (gold, lead) ◼ b. Semi-metals – minerals that are more fragile than metals and have lower conductivity (arsenic, bismuth). ◼ c. Nonmetals – nonconductive (sulfur, diamond) ◼ 7. Halides – minerals containing halogen elements combined with one or more elements D. Identification Tests ◼ 1. Hardness ◼ 2. Streak (True Color) ◼ 3. Acid Test – Use hydrochloric acid – Tests for carbonate (calcite) Caves can form rocks with calcite. Acid in groundwater dissolves the calcite