40Section 3: The Formation, Mining, and Use of Minerals
41How Do Minerals Form? Limestones As water runs along the surface of the Earth andseeps through the ground, it dissolves minerals andcarries them to largebodies of water, wherethey crystallize on thebottom.
42How Do Minerals Form? Evaporating Salt Water Minerals such as halite crystallize when salt waterevaporates.
43How Do Minerals Form? Metamorphic Rocks Changes in pressure, temperature, or chemicalmakeup can form new minerals such as garnet.
44How Do Minerals Form? Hot-Water Solutions Magma heats groundwater, which now more easilyreacts with and dissolves minerals. The mineralsthen crystallize out ofthe solution. Thisvein of gold wasformed this way.
45How Do Minerals Form? Pegmatites Magma can move upward into these teardrop-shapedbodies. Pictured here is a sample of tourmaline froma pegmatite.
46How Do Minerals Form? Plutons As magma moves up it may cool and solidify forming apluton.
47Mining Ore: A mineral deposit large enough and pure enough to be mined for profit.
48Mining Surface Mining Used to remove minerals located at or near the surface of the Earth.
49Mining Subsurface Mining Used to remove minerals located too deep within theEarth to be surface mined.
50Responsible Mining Potential mining problems: - Can disturb or destroy habitats- Waste products may pollute surface water andgroundwater
51Responsible Mining Potential mining problems: Solutions: - Can disturb or destroy habitats- Waste products may pollute surface water andgroundwaterSolutions:- Reclamation: return mined land to its original state- Reduce need for minerals by recycling
52The Use of Minerals Metallic Minerals - Have shiny surfaces - Do not let light passthrough them- Good conductors of heatand electricity
53The Use of Minerals Nonmetallic Minerals - Have shiny or dull surfaces - May let lightpass throughthem- Good insulatorsof electricity
54The Use of MineralsGemstones- Highly valued for beauty and rarity