Land and Water Use - Environmental Science - page 96

market-driven need for companies to extract as much as possible as fast as possible and as cheaply as possible.
However regulations exist to reduce environmental impact and help to conserve resources.

While the concept of mining applies to minerals and fossil fuels, this section addresses the mining of minerals.
Fossil fuel formation and extraction are addressed in Chapter 5.

Mineral Formation
Minerals are nonrenewable resources formed through geologic processes. Most minerals are found not in their
pure form but as an ore. An ore is a mixture of mineral elements packed together into naturally occurring mo-
lecular compounds. For example, galena is lead combined with sulfur (PbS) and is the most common form of
lead found in nature.

Minerals can be formed through a variety of processes. Some minerals are formed when molten magma cools
and the minerals it contains crystallize into deposits. Crystallization and, thus, mineral formation also can oc-
cur as water evaporates. Bodies of water contain dissolved minerals. When mineral-rich water evaporates, the
minerals are left behind. Since oceans are high in salt content, much of the minerals left behind by evaporating
water are salts. Minerals also can be formed as hot water cools. Minerals dissolve in hot water, but as water
cools it can hold fewer minerals in solution. The excess crystallizes into mineral deposits. This crystallization
due to cooling often occurs deep within the Earth and near hydrothermal vents in the ocean.

Mineral Extraction
The extraction of minerals is an invasive process that commonly has detrimental environmental impacts, such
as the following:

• Habitat destruction due to the removal of vegetation
• Soil erosion
• Acid runoff from extraction processes, contaminating soil and water
• Air pollution as a result of fossil fuel combustion from machinery operations and smelting processes

Minerals and resources are extracted from the Earth in the following ways:

• Surface mining: Removes the soil and rock covering mineral deposits. This technique is used when de-
posits are located relatively close to the surface. Once the mineral deposit is completely extracted, the
hole is commonly refilled with the original soil and rock.
• Mountaintop removal: When the tops of mountains are blasted off to access the resource. This tech-
nique is common in the coal mines of the Appalachian Mountains.
• Placer mining: Uses water to separate the heavier minerals from lighter mud and debris. This technique
is commonly used to extract deposits found in riverbeds.
• Open-pit mining: Involves digging in order to reach the desired resource. Some pits are so large that the
sides are terraced so that trucks can get in and out. Open pits are usually called quarries.
• Subsurface mining: Creates shafts deep underground to extract resources from pockets or seams of min-
erals. Dynamite blasts, drilling, and manual labor are used to remove rock and access the resource.

Impacts of Mining
Impact Common Use