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Mineral Formation. Pages 56-66. How do Minerals Form?. Recall that minerals form through naturally occurring processes There are two main ways: When melted materials cool Dissolved in water. Cool Your Crystals. Minerals form as liquid rock cools, either inside the crust or outside - PowerPoint PPT Presentation
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Mineral Formation
Pages 56-66
How do Minerals Form?
• Recall that minerals form through naturally occurring processes
• There are two main ways:– When melted materials cool– Dissolved in water.
Cool Your Crystals
• Minerals form as liquid rock cools, either inside the crust or outside– Magma: molten
material below the crust
– Lava : magma that reaches the surface.
• Deeper in the earth, magma cools slowly. Slow cooling means bigger crystals.
Olivine cools at 1200 degrees Celsius
Cool Your Crystals
• Faster cooling occurs closer to or at the surface. This means smaller crystals.
Cool Your Crystals
Quartz cools 700 degrees Celsius
• Problem: How does the cooling temperature affect crystal size?
• Hypothesis: Minerals that cool at a higher temperature
have larger crystals.
Minerals that cool at a lower temperature have smaller crystals.
Sizing Up the Problem
• Some elements dissolve into hot water below Earth’s surface
• This creates a solution:– A mixture in which one
substances dissolves in another.
Hot Water Solutions
• Heated water solution races upwards through cracks in the rock
• In the cracks, they crystallize to form veins:-- Narrow channels or slabs of minerals that are very different from the surrounding rock.
Hot Water Solutions
• Minerals also form out of solution when the water evaporates.
• This is what happens when salt water evaporates, leaving only the salt behind.
Formation by Evaporation
Mineral Deposits
• Ore: a mineral that contains a metal or economically useful mineral.
• Prospecting: searching for an ore deposit.– Geologists use features and rocks on the
surface.
• Mining – looking for ore deposits
1. Strip Mine2. Shaft Mines3. Open Pit Mines
Mining
• Strip Mine– Earth moving equipment scrapes away
soil to expose ore.
Mining
• Shaft Mines - network of tunnels that extend deep into the ground following the veins of ores.
Mining
TauTona
3.9 kilometers deep
• Open Pit Mines - use giant earthmoving equipment to dig a huge pit.
Mining
• Gemstones• Metals• Glass• Cement• Alloy
Uses of Minerals
How can we tell one mineral from another?