CH 7 RESOURCES AND ENERGY

Background  Earth’s crust contains useful mineral resources.  The processes that formed many of these resources took millions of years.  Scientists have identified more than 4,000 different minerals in Earth’s crust.  Many of theses minerals resources are mined for human use.

Background  Mineral resources can be:  Metals (Gold, Silver, Aluminum)  Nonmetals (Sulfur, quartz)  Metals are good for conducting heat and electricity  Nonmetals aren’t.  Metallic minerals are called native elements can exist in earth’s crust as nuggets  Most exist as compounds

Ores  Ores are mineral deposits from which metals and nonmetals can be removed profitably.  Example: Iron can be removed from naturally occurring deposits of the mineral magnetite and hematite.  Example: Mercury can be separated from ore cinnabar, and Aluminum from ore bauxite

How Ores Form  Formed from within cooling magma  Chromium, Nickel, Lead  As magma cools, dense metallic minerals sick, as the minerals sink, layers of these minerals accumulate at the bottom of the chamber to form ore deposits. Pg 155  Formed by Contact Metamorphism  Lead, Copper, Zinc  Contact Metamorphism is a process that occurres when magma comes into contact with existing rock, changing the existing rock.

How Ores Form  Formed by Contact Metamorphism (conc.)  Hydrothermal solutions Minerals dissolve in hot water, eventually come out of solution, forms in narrow cracks called “veins” Gold, Tin, Copper, Lead When there are many veins together they are called “lodes”  Formed by Moving Water  Minerals are released from rock as it breaks down  Streams carry dense minerals and the minerals become concentrated at the bottom of stream beds know as Placer Deposits.

Uses of Mineral Resources Pg 157  Gemstone- a mineral, rock, or organic material that can be used as jewelry or an ornament when it is cut and polished.  Look at Table 1 read all the potential uses of different minerals.

Mineral Exploration and Mining  During mineral exploration, people search for mineral deposits by studying local geology.  Airplanes that carry special equipment are used to measure and identify patterns in magnetism, gravity, radioactivity, and rock color.  Exploration teams also collect and test rock samples.

Mining  Subsurface Mining  Miners work underground to recover mineral deposits  Surface Mining  Close to Earth’s surface  Overlying rock is stripped away, Cu  Placer Mining  Dredging, large buckets scoop up the sediments. Dense minerals are separated from other sediment.  Undersea Mining  Nodules-lumps of minerals on the deep ocean floor, contain Fe, Ni, Mn,….difficult to mine.