Structure of the Earth and Mineralogy Environmental Science Earth Science Unit Environmental Science Earth Science Unit

Questions for Today 1.What is the Structure of the Earth? 2.What are Minerals? 3.What are the physical and chemical characteristics of Minerals? 4.What are Rocks? 5.How are Rocks Classified? 1.What is the Structure of the Earth? 2.What are Minerals? 3.What are the physical and chemical characteristics of Minerals? 4.What are Rocks? 5.How are Rocks Classified?

The History of the Planet The Earth is the third planet out of the “nine” planets in our solar system. Two types of planets in our solar system: –Terrestrial (1 st four) –Jovian (Last “five”) The Earth is the third planet out of the “nine” planets in our solar system. Two types of planets in our solar system: –Terrestrial (1 st four) –Jovian (Last “five”)

Interior Structure of the Earth The Earth has a radius of about 6371 km, although it is about 22 km longer at equator than at poles. Density, (mass/volume), Temperature, and Pressure increase with depth in the Earth. The Earth has a radius of about 6371 km, although it is about 22 km longer at equator than at poles. Density, (mass/volume), Temperature, and Pressure increase with depth in the Earth.

Interior Structure of the Earth The Earth has a layered structure. This layering can be viewed in two different ways: –Layers of different chemical composition –Layers of different physical composition The Earth has a layered structure. This layering can be viewed in two different ways: –Layers of different chemical composition –Layers of different physical composition

Interior Structure of the Earth Compositional Layering –Crust - variable thickness and composition Continental km thick Oceanic km thick –Mantle km thick, made up of a rock called peridotite. –Core km radius, made up of Iron (Fe) with some Nickel (Ni) Compositional Layering –Crust - variable thickness and composition Continental km thick Oceanic km thick –Mantle km thick, made up of a rock called peridotite. –Core km radius, made up of Iron (Fe) with some Nickel (Ni)

Interior Structure of the Earth Layers of Differing Physical Properties –Lithosphere - about 100 km thick (up to 200 km thick beneath continents), very brittle, easily fractures at low temperature. –Asthenosphere - about 250 km thick - solid rock, but soft and flows easily (ductile). –Mesosphere - about 2500 km thick, solid rock, but still capable of flowing. –Outer Core km thick, Fe and Ni, liquid –Inner core km radius, Fe and Ni, solid Layers of Differing Physical Properties –Lithosphere - about 100 km thick (up to 200 km thick beneath continents), very brittle, easily fractures at low temperature. –Asthenosphere - about 250 km thick - solid rock, but soft and flows easily (ductile). –Mesosphere - about 2500 km thick, solid rock, but still capable of flowing. –Outer Core km thick, Fe and Ni, liquid –Inner core km radius, Fe and Ni, solid

Minerals Minerals are the building blocks of Rock. A mineral is: –Naturally Formed (It forms on its own!) –Solid –With a definite chemical Composition –A Characteristic Crystalline Structure Minerals are the building blocks of Rock. A mineral is: –Naturally Formed (It forms on its own!) –Solid –With a definite chemical Composition –A Characteristic Crystalline Structure

Examples of Minerals Ice can be a mineral because of it’s solid form, it’s definite chemical Structure and crystalline structure Halite is naturally formed salt. Ice can be a mineral because of it’s solid form, it’s definite chemical Structure and crystalline structure Halite is naturally formed salt.

Important Minerals in Earth’s Crust O, 45.2% by weight Si, 27.2% Al, 8.0% Fe, 5.8% Ca, 5.1% Mg, 2.8% O, 45.2% by weight Si, 27.2% Al, 8.0% Fe, 5.8% Ca, 5.1% Mg, 2.8% Na, 2.3% K, 1.7% Ti, 0.9% H, 0.14% Mn, 0.1% P, 0.1% The Variety of Minerals we see depend on the chemical elements available to form them. In the Earth’s Crust the most abundant elements are:

Minerals in the Earth’s Crust Because of the limited number of elements in the earth’s crust, there are only about 3000 minerals known. Only 20 to 30 of these are common The most common minerals are based on Si and O and are called Silicates. Because of the limited number of elements in the earth’s crust, there are only about 3000 minerals known. Only 20 to 30 of these are common The most common minerals are based on Si and O and are called Silicates.

Rocks Rocks are aggregates of minerals that are held together to form a consolidated mass. The three general types of Rock are: –Igneous –Sedimentary –Metamorphic Rocks are aggregates of minerals that are held together to form a consolidated mass. The three general types of Rock are: –Igneous –Sedimentary –Metamorphic

Igneous Rocks Igneous Rocks are rocks that result from a melt – called magma. There are two types of Igneous Rocks: –Plutonic Rocks – form beneath the earth’s surface. Coarse Textured Ex: Granite and Gabbro –Volcanic Rocks – form above the earth’s surface. Fine textured Ex: Rhyolite, Andesite, and Basalt Igneous Rocks are rocks that result from a melt – called magma. There are two types of Igneous Rocks: –Plutonic Rocks – form beneath the earth’s surface. Coarse Textured Ex: Granite and Gabbro –Volcanic Rocks – form above the earth’s surface. Fine textured Ex: Rhyolite, Andesite, and Basalt

Sedimentary Rocks Rocks that form near the surface of the Earth through chemical precipitation from water or by cementation of loose fragments (sediments) Three types of Sedimentary Rocks: –Clastic – result from cementation of loose fragments. –Chemical - result from direct chemical precipitation from surface water. How Halite and Calcite is formed. –Biogeochemical – result from the chemical precipitation by living organisms. Limestone is the most common biogeochemical sedimentary Rock. Rocks that form near the surface of the Earth through chemical precipitation from water or by cementation of loose fragments (sediments) Three types of Sedimentary Rocks: –Clastic – result from cementation of loose fragments. –Chemical - result from direct chemical precipitation from surface water. How Halite and Calcite is formed. –Biogeochemical – result from the chemical precipitation by living organisms. Limestone is the most common biogeochemical sedimentary Rock.

Identifying Clastic Rocks Name of Particle Size RangeLoose Sediment Consolidated Rock Boulder> 256 mmGravel Conglomerate (if clasts are rounded) or Breccia (if clasts are angular) Cobble mmGravel Pebble2-64 mmGravel Sand1/16 -2 mmSandSandstone Silt1/256 – 1/16 mm SiltSiltstone Clay<1/256 mmClayClaystone, mudstone, and shale

Metamorphic Rocks Rocks that result when any kind of PRE-existing rock is buried deep in the Earth and subjected to HIGH temperature and pressures. –Most metamorphic rocks show a banded texture of the different sheets of silica –Examples: Slate and Schist Rocks that result when any kind of PRE-existing rock is buried deep in the Earth and subjected to HIGH temperature and pressures. –Most metamorphic rocks show a banded texture of the different sheets of silica –Examples: Slate and Schist