Presentation on theme: "Activator. Rock vs Mineral? Decide if each object shown better represents a rock or a mineral. Hold up the rock side or mineral side of your page. Example:"— Presentation transcript:
All minerals are hard, but some are harder than others. Scientists test the hardness of a mineral by trying to scratch it. Scientists use the Mohs Hardness Scale to rate a mineral’s hardness. Minerals at the top of the scale are soft and easy to scratch. Those at the bottom are hard and difficult to scratch. 1.Talc 2.Gypsum 3.Calcite 4.Fluorite 5.Apatite 6.Orthoclase/ Feldspar 7.Quartz 8.Topaz 9.Corundum 10.Diamond 1.Talc 2.Gypsum 3.Calcite 4.Fluorite 5.Apatite 6.Orthoclase/ Feldspar 7.Quartz 8.Topaz 9.Corundum 10.Diamond
Diamonds are the hardest minerals. It is almost impossible to scratch a diamond. Talc is the softest mineral. You can scratch it with your fingernail. Apatite and feldspar have medium hardnesses. Diamond – the hardest mineral talc – the softest mineral apatite feldspar
Some minerals leave a trail, or streak, when rubbed on a hard surface. Scientists classify minerals by the color of their powder. Hematite leaves a red-brown streak.
Crystal Systems The crystals of each mineral from atom by atom to form the mineral’s crystal structure. Geologists classify these structures into six groups based on the number and angle of the crystal faces. Group - Example Cubic - Magnetitie Hexagonal - Quartz Tetragonal – Rutile Orthorhombic - Sulfur Monoclinic - Azurite Triclinic – Microcline Feldspar
Cleavage and Fracture A mineral that splits easily along flat surfaces has the property of cleavage.
Fracture Fracture describes how a mineral looks when it breaks apart in an irregular way
Specific Gravity a mineral’s density in water is known as its specific gravity at a certain temperature
Examples The specific gravity of gold is 19.3 g/cm3 Aluminum’s specific gravity is 2.70 g/cm3
Special Properties Fluorescence – reacts to ultraviolet light Magnetic attraction Reacts to an acidRadioactive, Conducts electricity, etc.
Why is it important to learn about minerals? Minerals are made as part of the Earth’s constructive process. We use these minerals in many ways in our daily lives. Minerals are made as part of the Earth’s constructive process. We use these minerals in many ways in our daily lives.
Are minerals a renewable resource? Why or why not? No, it can take many years to replace the minerals as part of the Earth’s constructive process.
Part Three How do minerals form? How do minerals form? text pgs. 128-132 text pgs. 128-132
More about how minerals form In general, minerals can form in two ways: through crystallization of melted materials and through crystallization of materials dissolved in a liquid. The process through which atoms are arranged to from a material with a crystal structure is referred to as crystallization.
Minerals from Magma Minerals form as hot magma cools inside the Earth’s crust or as lava hardens on the surface. When liquids cool to a solid state, they form crystals. The size of the crystal depends on several factors: the rate at which magma cools, the amount of gas the magma contains, and the chemical composition of the magma all affect crystal size. When magma/lava cools slowly deep in the Earth’s surface, large crystals form. When magma/lava cools quickly, small crystals form.
Minerals from hot water solutions time lapse of growing crystal time lapse of growing crystal time lapse of growing crystal Sometimes minerals dissolve in solutions. A solution is a mixture in which one substance dissolves in another. When a hot water solution begins to cool, the elements and compounds leave the solution and begin to crystallize as minerals. Pure metals that crystallize underground form veins. A vein is a narrow channel or slab of a mineral that is different from the rock surrounding it. Often these mineral form where tectonic plates spread apart forming chimneys along the mid- ocean ridge. Other minerals can be seen when the solution evaporates. One example of this is the mineral halite (salt).
Mineral Resources Text pgs. 134-139 Minerals are the sources of metals, gemstones, and other materials used to make many products that we use today.
What is an ore? A rock that contains a metal or economically useful mineral is called an ore. Most metals do not occur in pure form. A metal usually occurs as a mineral in a combination of metal and other elements. Much of the world’s copper is found in an ore containing the mineral chalcopyrite. They must be separated from their other elements in the ore. Bauxite is an ore for aluminum.
Smelting Ores must be processed before the metals they contain can be used. After miners remove ore from a mine, smelting is necessary to remove the metal from the ore. In the process of smelting, an ore is melted to separate the useful metal from the other elements the ore contains. After smelting, additional processing may be needed to get rid of impurities. One example is the creation of steel, an alloy – a solid mixture of two or more metals. How steel is made