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Rocks&&MINERALS Minerals ROCKS Minerals EQ: How are minerals a part of rocks? What is a Mineral? • DEF: A naturally occurring, inorganic solid that has a crystal structure & a definite chemical composition. • Example: Quartz Minerals must be: • Naturally occurring made from nonliving things (fossils & coal are made from living things that died so are not considered minerals) Not man made Naturally-occurring • Never man-made • Ex: Like rocks Inorganic: • Means the mineral cannot come from things that were once living • Non Example: Coal – it is organic because it comes from plants that lived millions of years ago. Solid A 3-D geometric figure Not a liquid or a gas! Minerals must be: • Solid – Have a fixed shape and volume – Never livinginorganic Crystal: The repeating pattern of particles, line up when they form Like a snowflake pattern or rock candy 6 Different Crystal Systems: Cubic Hexagonal Tetragonal Orthorhombic Monoclinic Triclinic Ex: Magnetite Ex: Quartz Ex: Rutile Ex: Sulfur Ex: Azurite Ex: Microcline Feldspar Minerals must have: • Have a definite crystal structure – particles line up in a regular, repeating pattern. – flat sides called faces, that meet at sharp edges and corners. http://vasichkominerals.com/ Minerals must have: • A definite chemical composition – Always contains certain elements in the same proportion. http://www.eas.slu.edu/People/Students/woodhull/uraninite.html – Almost all minerals are compounds, (two or more different elements chemically joined). Definite Chemical Composition Certain elements form together in specific ways Like Hydrogen & Oxygen (H2O) and Carbon & Oxygen (CO2) form together to make these compounds Minerals Review • All minerals must: – Occur naturally in nature – Inorganic solid – Crystal structure – Definite chemical composition http://nature.ca/museum/press/2006/pr06-02-07_minstucson_e.cfm Physical Properties Identify Minerals Physical Properties include 6 “tests” you can perform on minerals to determine what type of mineral they might be. Properties of Minerals • Color first thing noticed about minerals http://www.nmnh.si.edu/rtp/students/2004/virtualposters/poster 1. Streak Test The color of the mineral’s powder that’s left behind when it is rubbed across a rough surface Example: Pyrite looks like gold but, it’s streak looks greenishblack (aka “fool’s gold”) Properties of Minerals • Streak • The color of its powder. • Not always the same as the color of the mineral. http://geology.csupomona.edu/alert/mineral/streak.htm 2. Luster Describes how light is reflected from the mineral’s surface. What does it look like? Properties of Minerals • Luster • The way a mineral reflects light. • Can be metallic or non-metallic. • Shiny or dull. • waxy, pearly, glassy. This is a gem stone called tourmaline it has a glassy luster Types of Luster – Metallic – Glassy – Waxy, Greasy, Pearly – Dull – Silky – Earthy Ex: Galena Ex: Topaz Ex: Talc Ex: Graphite Ex: Malachite Ex: Hematite 3. Density It’s a calculation (math problem!) Use a balance to find the mass Place the mineral in H2O to find the amount of water it displaces. This amount is the volume of the mineral. To find the density, divide mass by volume Ex: Sample of Olivine Mass = 237 g Volume = 72 cm3 Density = 237 g/ 72 cm3 = 3.3 g/cm3 Properties of Minerals • Density • Minerals will have a certain density regardless of the size of the sample. • Each mineral has its own density called specific gravity http://www.astronomynotes.com/cosmolgy/ 4. Cleavage One way minerals break Easily split along flat surfaces Ex: Mica & Feldspar 5. Fracture One way minerals break Break unevenly in irregular ways Chipped Shell-like Ex: Quartz Jagged points Ex: Copper & Iron Crumbles Ex: Clay 6. Mohs Hardness Scale A scale that ranks 10 minerals from softest to hardest. You can compare unknown minerals to the minerals on this scale Hardness can be tested by a Scratch Test A mineral can scratch any other softer mineral It can also BE scratched by any harder mineral Softest Mineral – Talc Hardest Mineral - Diamond Properties of Minerals • Hardness A measure of how easily a mineral can be scratched. http://www.info-diamond.co.uk Rocks classification • • • • • http://geology.com/rock-tumbler/tumbling-rough.shtml Texture Grain Minerals Color Origin of rocks Rock classification • Texture is how a rock looks and feels • texture in rocks is determined by the size, shape, and pattern of a rocks grains. ocal.wasp.uwa.edu.au/.../rock/rock16.jpeg Rock Classification • Grain – Size -- large, small – Shape --smooth, rough, round jagged – Pattern – rows, waves, swirls, beads or random patterns http://www.union.edu/PUBLIC/GEODEPT/COURSES/geo-10/metamorphic.htm Rock classification • Mineral composition – Rocks are made of more than one mineral blue.utb.edu/.../PHYS1417SPR00/Unit3Lec.html Rock classification Rocks & Minerals • Color rocks come in all sorts of colors Rock Classification • Origin of rocks • How were the rocks formed - magma - erosion and layering - heat and pressure Origin of rocks • Igneous rocks are formed from the cooling of magma or lava – Lava is magma that reaches the earth’s surface www.outreach.canterbury.ac.nz/.../igneous.jpg Origin of rocks • Sedimentary rocks are formed from other rocks that are broken into small particles and moved by erosion (wind or water) • The particles are squeezed or cemented together • Rocks are layered www.energyinst.org.uk/education/glossary/ Origin of rocks • Metamorphic rocks are formed from other rocks • Rocks have been pushed deep into the earth’s crust • Pressure from the earth above and heat from the mantle below cause them to change shape, color, grain and crystal structure http://www.classzone.com/books/earth_science/terc/content/visualizations/es0607/es06 07page01.cfm?chapter_no=visualization Rock cycle http://www.classzone.com/books/earth_science/terc/content/investigati ons/es0602/es0602page02.cfm