Rocks and Minerals
Rocks are made from Minerals Rocks are nothing more than a mixture of different mineral crystals. ***All three minerals are combined in a Granite rock Granite Quartz + Biotite + Feldspar = (mineral) (mineral) (mineral) (Rock) This is Continental Crust Intro Page 2
Rocks are made from Minerals Rocks are nothing more than a mixture of different mineral crystals. ***Both minerals combined make Basalt Pyroxene + Olivine = Basalt (mineral) (mineral) (rock) This is Oceanic Crust Intro Page 3
3 Types of Rocks Igneous Sedimentary Metamorphic
Igneous Rocks Formed from cooled Lava (from a volcano) and Magma (under the surface) As an Example: Liquid hot lava Basalt can become ***When the lava cools and turns into a solid, it can turn into Basalt! 5
Igneous Rock Recipe 1. Take some Minerals, water vapor & CO2 Mix well Quartz + Biotite + Feldspar 2. Add Heat Energy & Melt 3. Change Rock to Liquid Phase (Magma) 4. Remove from heat, let it Cool & Crystallize (Intrusive/Extrusive) 5. Igneous Rock Minerals + Heat 6
Examples of Igneous Rocks Granite Scoria Basalt Pumice Obsidian Click on the image to see how they are formed
Two Types of Igneous Rocks 1.Extrusive Igneous Rocks Cools on the surface of the earth (comes out of a volcano) Cools quickly Small crystals 2. Intrusive Igneous Rocks Cools under the surface of the earth Cools slowly Big crystals
Minerals & Crystals from Magma & Lava Extrusive Cooling: Lava cools Fast (Short Time = Small Crystals) Minerals form from hot magma as it cools inside the crust, or as lava hardens on the surface. When these liquids cool to a solid state, they form crystals. Size of the crystal depends on the mineral substance & the time it takes to cool down. Intrusive Cooling: Magma cools slowly (Long Time = Large Crystals) 9
Lava: Minerals & Crystal Size Extrusive: When the mineral material cools fast, it has smaller crystal size. Intrusive: When the mineral material cools slow, it has large crystals. Rhyolite Granite V. Extrusive: You can t see many individual crystals in Rhyolite =cooled very fast Intrusive: You can see individual crystals in Granite =cooled slowly 10
How Extrusive Igneous Rocks Form Extrusive = rocks that cool on the surface When magma from below rises and punches through, the minerals don t have time to crystallize therefore, they produce rocks with small crystals. Lava Flow (Outside) Magma (inside) The lava will quickly cool into solid rock! 11
Minerals & Crystals from Lava If magma cools very rapidly, it produces Glass NO CRYSTALS! No Time = No Crystals *(N = N) Holes are made when gasses escape as its cooling. Scoria Pumice Obsidian Rock Classification ***No visible crystals in either rock 12
How Intrusive Igneous Rocks Form Intrusive = rocks that cool below the surface of the earth When magma from below rises up, but does not make it to the surface, the minerals start to crystallize slowly and form large crystals. Magma Batholiths 13
Granite Batholiths Granite Granite contains large mineral crystals from cooling deep below the surface. Erosion has exposed the surface of these batholiths many millions of years later. 14
Sedimentary Rocks How They are Made Formed by sediments (pieces of rock, shells, or dead organisms) becoming cemented (stuck) together. Rock Classification Sedimentary Recipe Weathering & Erosion Rock Types
Sedimentary Rock Recipe 1. Rise to the Surface (Above the water) 2. Weather (Break up rock into sediment) 3. Erode (Carry away the sediment) 4. Deposition (Dropping the sediment) 5. Compaction & Cementation Rise to the Surface Weathering & Erosion Sedimentation & Deposition Compaction Cementation (stuck together) Sedimentary Rock Sedimentary Rocks ***Notice that different layers of sediments are forming 16
Weathering Weathering is where rock is broken down into smaller pieces. This happens when water freezes and cracks rock, when plant roots grow through the rocks, or by acids, etc. 17
Erosion Notice all the dirt in this stream which came from the surface of broken down rock. The removal of rock particles by wind, water, ice, or gravity. After the pieces have been created through weathering, they are carried away through erosion. Sedimentary Rocks 18
There are 3 Different Types of Sedimentary Rocks Organic (coal) Chemical (Gypsum) Clastic (Sandstone) From Living Stuff From Evaporation From Granules Glued Together Rock Classification Click on the image to learn more. Sedimentary Rocks
Organic Organic Sedimentary Rock is rock formed from once living materials. Coal (Organic) Limestone (Organic/Chemical) 20
Physical Properties of Organic Sedimentary Rock Made from parts of living things: Shells or fossil remains of other sea critters. Notice all the shells stuck together 21
Physical Properties of Organic Sedimentary Rock This limestone rock also formed through living things dying and piling up on the floor of the ocean. All this Limestone used to be on the bottom of an ocean! (ocean floor) In fact, this Limestone is made out of the chemical Calcium Carbonate! ***Limestone is made up of the Calcium (shells) and Carbon (bodies) from once living things (dead) in the water (oceans). 22
Clastic Clastic rock is rock formed from pieces of rock cemented together. Shale (Clastic) Sandstone (Clastic) Conglomerate (Clastic) 23
Physical Properties of Clastic Sedimentary Rock Clastic rock is rock that is glued to other rock. Conglomerate Rock Notice the rounded rocks glued in this rock. This is from rocks that have been eroded in a river bed. Take notice of small pieces of rock stuck together Breccia Notice the jaded rocks glued in this rock. This is from rocks that have been involved in flash floods. 24
Physical Properties of Clastic Sedimentary Rock Grainy Glued Sand, pebbles or rock fragments Appears to have glue like cement that keeps the grains together. Often forms linear layers Sandstone Notice the fine grain sand particles that are glued together in a linear formation. Back to Types 25
Chemical Chemical Sedimentary Rock is rock that is formed from dissolved minerals (Gypsum/Halite/Calcite) precipitating out of a water solution. Gypsum (Chemical) Limestone (Organic/Chemical) 26
Physical Properties of Chemical Sedimentary Rock Dolomite (Halite/Gypsum): Formed from evaporation water leaving dissolved minerals. Fine grains with several crystal faces. Dolomite 27
Metamorphic Rocks To Morph means to change it! Rocks that have changed. They were once Igneous or Sedimentary rocks that got buried DEEP underground. The heat and pressure from being deep underground changed the rocks. 28
+ HEAT Metamorphic Rock Recipe 1. Get some pre-formed existing rock (Igneous or Sedimentary will do) & bury it deep underground. Granite (Igneous) 2a. Add pressure and a mild amount of Heat (Not too hot) + Pressure + Pressure 3. Cool & (Re)-Crystallize Gneiss (foliated) 4. Metamorphic Rock 29
Foliated v. Non Foliated Geologists classify metamorphic rocks according to the arrangement of the grains that make up the rocks. Foliated Curvy thin lines of intergrown crystals Gneiss Non Foliated Intergrown crystals w/ no lines Quartzite 30
Crystals are Random in their locations Crystals line up in mostly straight lines + Pressure + Pressure Granite=large, randomly located crystals becomes Gneiss=smaller, lined up crystals 31
Foliation Mineral crystals aligned in parallel layers. Notice that the crystals have been squished into mostly straight lines. 32
Because of Heat & Pressure, We can Morph the Rocks into a New Rock. Granite (Igneous) Sandstone Shale Plus Heat & Pressure Plus Heat & Pressure Plus Heat & Pressure Gneiss (foliated) Quartzite (non foliated) Slate (foliated) 33
Limestone Sandstone Breccia Tufa Limestone Gneiss Quartzite Intrusive Inside Extrusive Outside Organic Clastic Chemical Foliated (Thin bands of Crystals) Non Foliated (Crystals are banded) Rock Classification Review Rocks Can Be Igneous Sedimentary Metamorphic Large Crystals Small Crystals Granite Rhyolite 34