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.
Minerals must have: A definite chemical composition –Always contains certain elements in the same proportion. –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
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
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 greenish- black (aka “fool’s gold”)
Properties of Minerals Streak The color of its powder. Not always the same as the color of the mineral.
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
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
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.
Rocks classification 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
Rock classification Mineral composition –Rocks are made of more than one mineral blue.utb.edu/.../PHYS1417SPR00/Unit3Lec.html
Rock classification 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
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
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 07page01.cfm?chapter_no=visualization