Rocks and Minerals

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Rocks and Minerals:

Rocks and Minerals

Differences between minerals and rocks:

Differences between minerals and rocks A mineral is a naturally occurring solid with a definite chemical composition and a specific crystalline structure. A rock is an aggregate of one or more minerals.

What are Rocks?:

What are Rocks? A rock is a naturally occurring solid mixture of one or more minerals, or organic matter Rocks are classified by how they are formed, their composition, and texture Rocks change over time through the rock cycle

The Rock Cycle:

The Rock Cycle

Igneous Rocks:

Igneous Rocks Igneous rock begins as magma. Magma can form: When rock is heated When pressure is released When rock changes composition Magma freezes between 700 °C and 1,250 °C Magma is a mixture of many minerals

Igneous Rocks:

Igneous Rocks Felsic : light colored rocks that are rich in elements such as aluminum, potassium, silicon, and sodium Mafic : dark colored rocks that are rich in calcium, iron, and magnesium, poor in silicon Coarse-grained : takes longer to cool, giving mineral crystals more time to grow Fine-grained : cools quickly with little to no crystals

Igneous Rocks:

Igneous Rocks Felsic Mafic Coarse-Grained Fine-Grained Granite Gabbro Basalt Rhyolite

Igneous Rocks:

Igneous Rocks Intrusive Igneous Rocks : magma pushes into surrounding rock below the Earth’s surface Extrusive Rocks : forms when magma erupts onto the Earth’s surface (lava), cools quickly with very small or no crystals formed

Igneous Rocks:

Igneous Rocks Obsidian What is Obsidian? Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form. Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form. Is this rock Felsic or Mafic ? Is it fine-grained or coarse-grained? Is this rock Intrusive or Extrusive? Mafic , fine grained, extrusive

Sedimentary Rocks:

Sedimentary Rocks Sedimentary rock is formed by erosion Sediments are moved from one place to another Sediments are deposited in layers, with the older ones on the bottom The layers become compacted and cemented together

Sedimentary Rock:

Sedimentary Rock Sedimentary Rocks are formed at or near the Earth’s surface No heat and pressure involved Strata – layers of rock Stratification – the process in which sedimentary rocks are arranged in layers

Sedimentary Rock:

Sedimentary Rock Clastic – made of fragments of rock cemented together with calcite or quartz Breccia is a term most often used for clastic sedimentary rocks that are composed of large angular fragments (over two millimeters in diameter). The spaces between the large angular fragments can be filled with a matrix of smaller particles or a mineral cement that binds the rock together.

Sedimentary Rock:

Sedimentary Rock Chemical sedimentary – minerals crystallize out of solution to become rock Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO 3 ) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris.

Sedimentary Rock:

Sedimentary Rock Organic sedimentary – remains of plants and animals Coal is an organic sedimentary rock that forms from the accumulation and preservation of plant materials, usually in a swamp environment. Coal is a combustible rock and along with oil and natural gas it is one of the three most important fossil fuels.

Metamorphic Rock:

Metamorphic Rock Meaning to change shape Changes with temperature and pressure, but remains solid Usually takes place deep in the Earth

Metamorphic Rocks:

Metamorphic Rocks Contact Metamorphism – heated by nearby magma Increased temperature changes the composition of the rock, minerals are changed into new minerals Hornfels is a fine-grained non-foliated metamorphic rock produced by contact metamorphism igh&fr=t

Metamorphic Rocks:

Metamorphic Rocks Regional Metamorphism – pressure builds up in rocks that is deep within the Earth Large pieces of the Earth’s crust collide and the rock is deformed and chemically changed by heat and pressure

How minerals form:

How minerals form Minerals are crystals Two ways: Cooling magma Crystalizing aqueous mineral solution

From lava:

From lava The cooling of the lava causes it to form into crystals

Size of crystals depends on –:

Size of crystals depends on – the rate at which the magma/lava cools the amount of gas the magma/lava contains the chemical composition of the magma/lava Fast Slow

Minerals formed by Evaporation:

Minerals formed by Evaporation When ancient seas slowly evaporated, minerals formed (halite, gypsum, calcite)

Minerals from Hot Water Solutions :

Minerals from Hot Water Solutions Minerals dissolve in hot water underground When the solution cools, the minerals crystallize

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