Section 1: Mineral Resources Preview Objectives Mineral Resources Ores Uses of Mineral Resources Mineral Exploration and Mining The Formation of Ores and Placer Deposits Comparing Metals, Nonmetals, and Metalloids

Objectives Explain what ores are and how they form. Identify four uses for mineral resources Summarize two ways humans obtain mineral resources

Mineral Resources Mineral resources can be either metals, such as gold, U, silver, Ag, and aluminum, Al, or nonmetals, such as sulfur, S, and quartz, SiO2. Metals can be identified by their shiny surfaces, as good conductors of heat and electricity, and they tend to bend easily when in thin sheets. Most nonmetals have a dull surface and are poor conductors of heat and electricity.

Ores Ores *. Metallic minerals such as gold, silver, and copper, Cu, are called native elements and can exist in Earth’s crust as nuggets of pure metals. Most other minerals in Earth’s crust are compounds of two or more elements.

Ores, continued Ores Formed by Cooling Magma Some ores, such as chromium, Cr; and nickel, Ni, form as the magma cools and the dense metallic minerals sink. As the minerals sink, layers of these minerals accumulate at the bottom of the magma chamber to form ore deposits. Ores Formed by Contact Metamorphism lode *.

Ores, continued Ores Formed by Contact Metamorphism, continued Heat and chemical reactions with hot fluids from the magma can change the composition of the surrounding rock. This process is called. Some ores, such as copper, Cu; and zinc, Zn, form by contact metamorphism. Contact metamorphism also occurs when hot fluids called hydrothermal solutions move through small cracks in a large mass of rock. When the minerals from the surrounding rock dissolve into the hydrothermal solution, new minerals will precipitate from the solution and form narrow zones of rocks called veins.

Ores, continued Ores Formed by Moving Water placer deposit * The movement of water helps to form ore deposits. Tiny fragments of native elements, such as gold, Au, are released from rock as it breaks down by weathering. Streams carry the fragments until the currents become too weak to carry these dense metals, which collect in placer deposits.

Uses of Mineral Resources gemstones * Metallic ores are sources of valuable minerals and elements, like gold, Au, platinum, Pt, and silver, Ag. Some nonmetallic minerals display extraordinary brilliance and color when they are specially cut for jewelry. Other nonmetallic minerals, such as calcite and gypsum, are used as building materials.

Mineral Exploration and Mining During mineral exploration, people search for mineral deposits by studying local geology. Exploration teams also collect and test rock samples to determine whether the rock contains enough metals to make a mine profitable. Airplanes that carry special equipment are used to measure and identify patterns in magnetism, gravity, radioactivity, and rock color.

Mineral Exploration and Mining, continued Subsurface Mining Subsurface mining mines for minerals located below Earth’s surface Surface Mining Surface mining strips overlying rock material to reveal mineral deposits that are located close to Earth’s surface. Placer Mining Placer mining scoop up and separate the sediment from placer deposits to search for minerals. Undersea Mining Nodules are lumps of minerals on the deep ocean floor. However, because of their location, these deposits are difficult to mine.

The Formation of Ores and Placer Deposits The diagram below shows how ores form in placer deposits.