Transcript Minerals
Building a House Out of Minerals A roof is a barrier to snow and rain. What mineral is used in clay singles to cover the plywood sheets on the roof? Cement is used for the foundation and chimney of a house. Cement contains this mineral which is a source of calcium. ___________________ ___________________ Exterior walls can be made of things such as aluminum or steel siding or brick. What is one mineral that could be found in aluminum siding? Interior walls shape the rooms in a house. The wallboard covers the walls and is soft so that holes can be drilled in it for outlets and nails can be used to hang pictures. What mineral is wallboard made of? ___________________ ___________________ Metal pipes are commonly used to carry fresh water into the house. In the 1950’s a poisonous mineral was used in plumbing, what was it? ___________________ Windows let in visible light and allow us to see outside. What clear mineral is used to make window glass? Electrical wiring conducts electricity most wiring in made of metal. What mineral is often used for wiring? ___________________ Word Bank: Aluminum, Lead, Gypsum, Copper, Quartz, Illite (clay), Calcite ___________________ Minerals versus Rocks Composition and Structure of Minerals Properties of Minerals The Star of Bombay Mineral Groups 182-carat star sapphire Mineral Resources Minerals Versus Rocks • A rock is an aggregate of minerals • Minerals are the building blocks that make up rocks Varieties of Minerals More than 3000 different minerals Quartz Beryl (aquamarine) Olivine (Peridot) Native Copper Definition of Mineral • • • • • Naturally occurring Solid Inorganic (never living) Definite chemical composition Orderly internal structure of atoms Tetragonal Cubic Hexagonal Graphite Diamond Chemical formula: C Chemical formula: C How can 2 minerals with the same composition be so different? What’s the point here? “Internal Arrangement of Atoms” controls most physical properties! Mineral Formation 1. Cooling of magma-molten rock beneath the earth’s surface – if it cools fast small crystals – if it cools slowly large crystals 2. Compounds dissolved in a liquid (water); liquid evaporates & leaves behind crystals • Most minerals made up of only 8 elements these 8 elements make up 98% of Earth’s crust Relative abundance of the most common elements in the Earth’s crust Element Approximate Percentage by Weight Oxygen (O) 46.6% Silicon (Si) Aluminum (Al) Iron (Fe) Calcium (Ca) 27.7% 8.1% 5.0% 3.6% Sodium (Na) Potassium (K) 2.8% 2.6% Magnesium (Mg) 2.1% All Others 1.7% 100% Total Mineral Groups – Silicates: contains silicon + oxygen + one or more other elements (Most common rock forming minerals are silicates) – Carbonates: 1 carbon + 3 oxygen + other elements – Oxides: 2 oxygen + other elements – Sulfides: sulfur + other elements – Sulfates: 1 sulfur + 4 oxygen + other elements – Halides: chlorine, fluorine, bromine, or Iodine + other elements – Native elements: elements that are uncombined Silicates Quartz SiO2 Mica KAl2(AlSi3O10)(OH,F,Cl)2 Can you find the “silica” ? Silica Structure 4 oxygen atoms for every 1 silicon atom Carbonates Calcite Mineral Identification • • • • • • Hardness Color Streak Test Luster Crystal Form Cleavage / Fracture Mineral Properties Hardness - A measure of the resistance of a mineral to abrasion or scratching. Mohs Hardness Scale Relative Scale Hardest Softest 10 9 8 7 6 5 4 3 2 1 Mineral Diamond Other Objects Corundum Topaz Quartz K-Feldspar 5.5 Glass, Pocketknife Apatite Fluorite 3.5 Copper Penny Calcite 2.5 Fingernail Gypsum Talc Mineral Properties Color Colorless quartz Purple quartz (amethyst) Brueno Jasper Mineral Properties Streak – The color of a mineral in its powdered form. The Mineral Hematite Always Has a Red Brown Streak Whether It Is the Metallic or Earthy Variety. Mineral Properties Luster – the appearance or quality of light reflected from the surface of the mineral. • Metallic vs. nonmetallic • Nonmetallic – vitreous (glassy), pearly, silky, resinous, and earthy Amethyst with vitreous luster Mineral Properties Crystal form – the external expression of a mineral’s internal orderly arrangement of atoms. Pyrite – Cubic Crystals Quartz -Hexagonal Crystals Mineral Properties Halite Calcite Cleavage – The tendency of a mineral to cleave, or break, along planes of weak bonding. Fluorite Multiple cleavages in fluorite, halite and calcite Simple cleavage in micas 1 plane - Micas 3 planes – Halite (salt) 2 planes – K Feldspar 3 planes (rhombo.) - Calcite Mineral Properties Conchoidal fracture in quartz FractureMinerals that do not break along cleavage planes are said to possess fracture Mineral Properties Specific gravity – compares the weight of a mineral to the weight of an equal volume of water. High specific gravity of galena. Additional Properties • Effervescence - Calcite and powdered dolomite will effervesce (fizz) in dilute hydrochloric acid (HCl) • Smell- Sphalerite will give off a rotten-egg smell when streaked on a streak plate. (Note: pure sulfur does not smell like rotten eggs!) • Magnetism- Magnetite (AKA Lodestone) will pick up paper clips (weak samples will only be able to pick up staples) • Taste- Halite is rock salt and will taste salty. *Do not taste the samples since some have been tested with acid to see if it is calcite. • Fluorescence- some minerals (mostly forms of calcite) will glow in fluorescent colors under a black (UV) light. • Double refraction- some clear forms of calcite (Iceland Spar) will make a double image of words. Additional Properties Fluorescence Double refraction Uses of Minerals • Gems: highly prized minerals because they are rare and beautiful – Most gems are brighter and more colorful than common samples of minerals – Ex: Emeralds, rubies, diamonds – Ex. Amethyst: a form of quartz with traces of iron, sapphires – Trace amounts of elements can make some gems more rare than others = More money Uses of Minerals • Ores: a mineral is an ore if it contains a useful substance that can be mined for a profit – Ex. Al from bauxite – Fe from hematite – Titanium from rutile Asbestos • A mineral with threadlike, flexible fibers – Used for insulation and fire protection = doesn’t burn or conduct heat – When these fibers become loose and airborne → often get into the lungs where they’ve been known to cause cancer (carcinogen)