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Plate Boundaries Review Places where plates move apart are called _____________ boundaries. divergent When continental plates diverge a rift valley ___________ is formed. When two oceanic plates converge what is an island arc and a trench created? _________________ The Appalachians formed mainly from continental plate collisions and therefore are a __________ mountain range. folded Convection currents The force moving the plates is ____________ . Open Book Pop Quiz 25 minutes to complete No talking If you are caught talking it will be considered cheating and you will receive a Zero and after school detention. Igneous Rocks-’Fire’ Rocks • https://www.youtube.com/watch?v=PrN7jygu 4cQ • What are igneous rocks? • Write 3 facts from the video. Igneous Rocks and Minerals • The smallest part of an element that has all the chemical characteristics of that element is an Atom • A substance that cannot be broken down into smaller substances is an Like Hydrogen, Carbon, Lead! Element • A naturally occurring inorganic substance with a definite chemical composition and a crystalline structure is a Mineral • A combination of minerals that can contain organic matter. Rock In your notes • ORGANIZE THE BUILDING BLOCKS OF ROCKS Atom Element Mineral Rocks Warm-Up • Arrange the following in order from smallest to largest: • Mineral • Rock • Atom • Element IGNEOUS ROCKS • Form by solidification (crystallization) of melted minerals • At the surface, LAVA hardens to form EXTRUSIVE rocks with tiny (FINE-GRAINED) crystals or GLASSY (no crystal) TEXTURES • Beneath the surface, MAGMA hardens to form INTRUSIVE rocks with easily visible (COARSE-GRAINED) crystal texture. Igneous Rocks Are Separated into Two Main Categories EXTRUSIVE INTRUSIVE Igneous Rocks • Igneous rocks are rocks that are formed from the crystallization of magma. Heat and melting Magma Cooling and crystallization Igneous Rocks Igneous Rocks are Categorized by Texture • Texture is determined by cooling time – Glassy Cooled very fast Cooled fast – Fine Grained – Course Grained Cooled slowly – Very Course Grained Cooled very slowly Rocks Melt into Magma or Lava • Magma is molten (melted) rock below the ground. • Lava is molten rock above the ground • The heat that melts rock comes from the mantle. Mineral Content Affects Magma • The difference in melting points of minerals causes partial melting. Minerals • • • • Natural Solid Inorganic Definite chemical composition • Crystal structure due to internal arrangement of atoms http://www.minerals.net/gemstone/index.htm http://www.mii.org/www.mii.org General Facts about Minerals • Between 2 - 3,000 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. Less than a dozen are common in most rocks • Quartz • Feldspar (group) • Muscovite (white mica) • Biotite (black mica) • Calcite • Pyroxene • Olivine • Amphibole (group) • Magnetite, limonite, and other iron oxides • Pyrite Minerals are identified by their key characteristics • hardness • crystal shape (form) • luster • color • streak • cleavage/fracture • density (specific gravity) • special properties --reaction to acid --fluorescence --salty taste --magnetism Mineral Hardness • Ability to scratch another mineral • Mohs scale from 1 (talc) to 10 (diamond) • Quartz (most common mineral and most dust particles) is 7 http://mineral.galleries.com/minerals/elements/diamond/diamond.htm Crystal Shape (Form) • External structure due to internal arrangement of the atoms • Six basic groups of shapes, with about three dozen variations http://www.minerals.net/mineral/carbonat/aragonit/aragoni1.htm Luster • Describes how light reflects off the surface • Main categories are “metallic” and “nonmetallic” • Non-metallic includes “dull,” glassy,” waxy,” “pearly,” and othershttp://www.min erals.net/mineral/sulfid es/pyrite/pyrite2.htm http://www.minerals.net/mineral/sulfides/pyrite/pyrite2.htm Color • results from ability to absorb some wavelengths and reflect others • some minerals have characteristics colors • others vary due to chemical differences or impurities (atoms mixed inside the main elements) http://www.minerals.net/mineral/carbonat/calcite/images/4assortd.htm Streak • Color of the powder when rubbed on a “streak plate” (unglazed porcelain) • May be same as hand-specimen or different • Some paint is based on powdered minerals (streaks). http://www.minerals.net/mineral/oxides/hematite/hematit6.htm Mineral cleavage/fracture • Some minerals split along flat surfaces when struck hard--this is called mineral cleavage • Other minerals break unevenly along rough or curved surfaces--this is called fracture • A few minerals have both cleavage and fracture Density (Specific Gravity) • All minerals have density (mass / volume), but some are very dense • Examples include galena, magnetite, and gold • Specific Gravity is the density of the mineral compared with density of water http://www.minerals.net/mineral/elements/gold/gold1.htm Special Characteristics-the “Acid Test” Carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing CO2 gas) Special Characteristics-Fluorescence • Some minerals will glow when placed under short-wave or long-wave ultraviolet rays • Franklin and Ogdensburg NJ are famous for their fluorescent minerals http://www.sterlinghill.org/Tour%20information.htm Special Characteristics-Salty Taste • DO NOT TASTE MOST MINERALS! • Halite is the exception--it will taste salty http://mineral.galleries.com/scripts/item.exe?LIST+Minerals+Halides+Halite Special Characteristics-Magnetism • Many iron minerals will produce an invisible magnetic force field • “Lodestone” was used by Vikings more than 1,000 years ago as compasses http://www.minerals.net/mineral/oxides/magnetit/magneti4.htm