Rocks N Minerals Rockin in the USA!!!!
3 Major Rock Types • 1. Igneous Rock • 2. Sedimentary Rock • 3. Metamorphic Rock
Igneous Rock • Means “From Fire” • Forms when magma cools and hardens • Lava rock
2 Groups of Igneous Rocks • 1. Intrusive Igneous Rock: Cooling of magma deep below the earth’s surface. • Have large crystalline grains • 2. Extrusive Igneous Rock: Rapid cooling of lava on the earth’s surface. • Fine grained rock
Igneous Texture • Size of the crystalline grains in rock • Depends on rate of cooling • Slower cooling = more grains • Granite • Intrusive have larger grains • Porphyry: has a mixture of large and small crystals • Igneous rocks cooled very fast will look like glass. • Obsidian
Igneous Composition • Determined by composition of magma the rock was formed from • Divided into 3 categories: • 1. Felsic • 2. Mafic • 3. Diorite
Felsic • High in silica • Light coloring of their mineral crystals • Ex. Granite and obsidian
Mafic • Low in silica but rich in iron • Have dark colored mineral crystals • Ex. Basalt and gabbro
Diorite • Include little or no quartz • Contain coarse grain diorite
Warm Up Questions??? • 1. What are the three main types of rocks? • 2. Slow cooling of a rock is called ____________. • 3. Fast cooling of a rock is called______________. • 4. Please name one rock which cools slowly. • 5. Please name one rock that cools quickly. • 6. Which rocks make up continental and oceanic crust?
Weathering • Forces of nature break down rocks into small particles called sediment • Wind, water, and ice
Erosion • Movement of particles of rock due to weathering. • Particles are loosened and moved
Sedimentary Rocks • Rocks are broken down due to erosion • Very small rock sediments are collected in streams, rivers, and oceans. • Sediments compact • Harden and form new rocks
Compaction and Cementation • Processes that form sedimentary rocks • Various types of rock sediments accumulate • Compact and become thick layers • Weight and pressure cement sediments into solid rock • Minerals left between sediments act as cement
Sedimentary Rock Types • 1. Clastic: separate fragments become compacted into solid rock. • 2. Chemical: Form from dissolved minerals • 3. Organic: form from the remains of organisms.
Clastic Sed. Rocks • 1. Conglomerate: Rock composed of round, pebble sized fragments. • 2. Breccia: Rock composed of pebble sized fragments with sharp, angular corners.
Chemical Sed. Rocks • Minerals dissolve in water • Leave behind deposits • Dry and harden into rocks • Ex. Rock Salt
Organic Sed. Rocks • Formed from the remains of living things • Ex. Coal, and Chalk
Stratification • Layering of sedimentary rocks • Occurs when there is a change of sediment being deposited
Fossils • Usually found in sedimentary rocks • Animal or plant is buried • Sediments pile up and harden • Hard bones and teeth dissolve • This leaves an impression in the rock
Metamorphic Rock • Changing of one type of rock to another by heat, pressure, and chemical processes. • Form deep beneath the surface • All metamorphic rock is formed from existing igneous, sedimentary, or metamorphic rock.
Metamorphic Cont. • Heat and pressure semi melt the rock and cause certain minerals to change into other chemicals. • Parallel bands running through the rock
Classification of Met. Rock • Classified according to structure • Foliated: have visible parallel bands • Mineral bands separate by density under pressure • Slate, schist, and gneiss • Unfoliated: without visible bands • Quartzite and marble
Rock Cycle • Any of the three major types can change into another type. • Geological forces have the ability to change one rock type to another. • Rocks are recycled throughout these three forms
Question 1 • Please explain how igneous rock can turn into sedimentary rock during the rock cycle.
Question 2 • Please explain how sedimentary rock turns into igneous rock.
Question 3 • Please explain how sedimentary rock can turn into metamorphic rock.
Question 4 • Please explain how it is possible for metamorphic rock to become another metamorphic rock.
Minerals • A natural, inorganic, crystalline solid. • The basic elements of the earth’s crust. • Over 3,000 total • 20 Common
Characteristics of Minerals • Each mineral has specific properties • Mineral Properties: • 1. Color • 2. Luster • 3. Streak • 4. Cleavage and Fracture • 5. Hardness • 6. Crystalline Shape • 7. Density • 8. Magnetism
Color • Unreliable identification • Some minerals have distinct colors • BUT • Some minerals will change color when exposed to different elements.
Luster • Light refracted from the surface of a mineral • Metallic and nonmetallic luster • Glassy • Waxy • Pearly • Brilliant- Diamond