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 the Important Minerals in the Earth’s Crust? 5.How are Minerals Formed? 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 the Important Minerals in the Earth’s Crust? 5.How are Minerals Formed?

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.

Formation of Minerals Minerals are formed in nature by a variety of processes. Among them are: –Crystallization from melt –Precipitation of Water –Precipitation from living organisms –Change to a more stable state –Precipitation from vapor Minerals are formed in nature by a variety of processes. Among them are: –Crystallization from melt –Precipitation of Water –Precipitation from living organisms –Change to a more stable state –Precipitation from vapor