Physical Geology Mineral and Mining Resources

Ore Minerals  Minerals that are valuable and economical to extract are known as ore minerals  Minerals that have no commercial value are called gangue minerals  Several separation techniques are used to separate ore or gangue minerals

Ore Minerals  Ore minerals are further refined to extract the valuable elements  For mining to be profitable, the price of the final product must be greater than the costs of extraction and refining.

Mineral Resources and Their Uses  Some minerals are of major economic and industrial importance  Some metals can be pressed into various shapes or stretched very thinly without breaking  Others are good conductors of heat and electricity  Some are prized for their durability and resistance to corrosion.

Mineral Resources and Their Uses  Often two or more metals are combined to form alloys  Alloys are important because they combine the most desirable properties of the metals used to make them

Mineral Resources and Their Uses  Some nonmetallic minerals are called gemstones and are prized purely for their beauty, rarity, or durability  Important gemstones include:  Diamond  Ruby  Sapphire  Emerald  Aquamarine  Topaz  Tourmaline

Mineral Exploration  The first step in finding an ore deposit is exploring rock for mineralization  Planes can identify patterns in gravity, magnetism, or radioactivity  Data and aerial photographs can be used to create geologic maps of the surface

Mineral Exploration  Samples are analyzed to determine ore grade  If the ore grade is high enough and the deposit extensive enough, the cost to open a mine may be warranted

Types of Mining  Subsurface Mining  Surface Mining  Placer Mining

Subsurface Mining  Ore deposits that are usually found 50 m or more beneath Earth’s surface are mined via subsurface mining  The most common method is room-and- pillar mining used to mine coal and salt

Subsurface Mining  Between the rooms, pillars of coal are left standing to support the roof  When the mining of rooms is completed, the pillars are then removed, beginning with pillars at the farthest point in the mine.

Surface Mining  Surface mining methods are used when ore deposits are located close to Earth’s surface  Open-pit mining is a method that is often used to mine large quantities of near-surface ore  Coal and metals like copper are mined using open-pit method  Ore is mined downward, layer by layer

Placer Mining  When rock weathers, minerals within the rock are released  These minerals are concentrated by wind and water into surface deposits called placer deposits  The most important place deposits are stream places

Undersea Mining  The ocean floor contains significant mineral resources, which include diamonds, precious metal such as gold and silver, mineral ores, and sand and gravel  Since the late 1950s, several attempts have been made to mine the ocean  Land-based companies can mine mineral more cheaply is a main reason undersea mining is unsuccessful.

Mining Reclamation  Mines on land in the United States are regulated by federal and states laws  Reclamation  The process of returning land to its original or better condition after mining is completed is called reclamation

Mining Reclamation  The Surface Mining Control and Reclamation Act of 1977 created a program for the regulation of surface coal mining on public and private land  The act set standards that would minimize the surface effects of coal mining on the environment.