12-4-17 ROCK CYCLE NOTES Why care about Rocks? Energy & Commerce Fossil Fuels Gems Countertops & other building materials History of the Earth Dinosaurs, Past Climates, Pangaea Other Planets Meteorites Rock Samples (from missions) Careers Geologists, Archeologist, Climatologist, Engineers, Architects, Artists Made Made Rocks up of Minerals up of Elements Minerals Naturally occurring (not manmade) Solid Inorganic/Non-living (some exceptions come from living things that have died) Fixed chemical formula Crystalline structure Minerals (examples) Feldspar - most commonly found in granite, this mineral is used mostly as a building material. Gypsum - is a very soft mineral with a variety of uses, most commonly in drywall. Pyrite is commonly known as fools gold. Quartz (silica) - is the most abundant mineral on earth. Minerals (examples) Halite(table salt) is a mineral. Sugar is a crystalline solid but comes from plants, sugar cane. This classifies it as an organic compound and so is not a mineral. Coal on the other hand also comes from plants (organic) and is generally considered a mineral. 1
What are Rocks anyway? A solid, naturally occurring, make up of one or more mineral(s) Not organic Constantly changing forms Main types Igneous Metamorphic Sedimentary What are Rocks made of? Some rocks are just composed of just one mineral. (ex: quartz) Most rocks are a mixture of several minerals. (ex: Granite & Gneiss) 3 Types of Rocks Igneous Sedimentary Metamorphic Rocks are classified by the processes under which they were formed. Rolling Stones are always changing Destruction of rocks; Faults (earthquakes) Landslides Subduction zones (melting) Erosion & Weathering Production of rocks; Sedimentary Basins Folded Mountains Volcanos (islands and mountains) Hot spots Sedimentary Basins a low area in the Earth s crust, of tectonic origin, in which sediments (sand, sea life, mud etc.) accumulate range in size from hundreds of meters to large parts of ocean basins Where most of the sedimentary rocks form How to identify rocks? Color Luster (Shine) Density Fracture Cleavage Vesicular - Bubbles Tenacity - toughness Hardness scratch test Transparency Magnetism Crystal Formation (size of crystals) Scientist used to lick and taste rocks! Not a good idea there is a lot of Arsenic out there! My rocks have been handled a lot, So don t lick my rocks.. eww 2
Rock Cycle 11/29/2017 General Characteristic of Rocks Igneous Metamorphic Sedimentary Crystals Glassy Bubbles Shiny Colorful Warped Distorted Bands Flakes Dense Dull Layers Fossils Fragments Sandy Sedimentary Rock Latin for settling Sediments of different types of rocks together into layers. Sediments include, salt, sand, mud, etc. Processes; Weathering, Deposition, Erosion, Compaction, Cementation Sandstone Halite (salt) Coal Shale Metamorphic Rock Latin = Meta - form Morph - change When rocks are changed due to heat and pressure. Has to be near a great deal of heat like in the mantle. (in the mantle then cooling would be igneous) Igneous Rock Latin for fire Formed when magma cools (lava) and makes crystals, bubbles, or a shiny surface. The rate at which they cool determines type. Basalt Granite Pumice Obsidian Marble Slate Gneiss Underground- magma cools slowly we call this intrusive. Above ground - magma cools quickly we call this extrusive. Cooling Melting Weathering And Erosion Igneous Rock Identification Chart K- extension Helps us to identify rock bases on characterizes Melting Heat and Pressure Weathering And Erosion Weathering And Erosion Compaction And concreting Heat and Pressure 3
Crystal size Grain Size Description Igneous rocks have Intergrown Crystals Not Intergrown Where it was formed? Outside the volcano: Extrusive Inside the Earth: Intrusive Bubbles? Yes= Vesicular Scoria Neither Light nor Dark Very Light Bubbles? No=Non-vesicular Color NotVery Light Light Not Very DarkVery Dark Dark Darkest Lightest 4
Density Very Light Light Medium Density Dense Very Dense Finding The Minerals Identify the rock. Unless you have other information, work in the middle of the rock s box. This is the amount of Potassium Feldspar in the rock. This is the amount of Quartz in the rock. This is the amount of Plagioclase Feldspar in the rock. Use tick marks on a scrap paper to measure the percentage. Potassium Feldspar 25% Quartz 40% 5
Practice Name a light-colored, fine-grained rock with no bubbles. Name a coarse-grained, dense rock. Name a very light-colored, glassy, extrusive rock with bubbles. 6