2.3 Minerals are valuable resources.
Chapter 2 Big Idea: Minerals are basic building blocks of Earth.
Remember: Minerals are all around us.
A mineral is identified by its properties.
1. magma- molten rock inside the earth
2. lava- molten rock that has reached Earth’s surface
3. ore- rocks that contain enough of a mineral to be mined for a profit
Minerals have many uses in industry.
· Mineral deposits are sources of:
- metals for cars and airplanes
- quartz and feldspar for glass
- fluorite and calcite for toothpaste
- silver compounds for photographic film
- mica and talc for paint
Minerals have many uses in the arts.
· Birthstones are beautiful gemstones; this tradition is hundreds of years old.
· Gemstones are cut, polished and ground to increase beauty and sparkle.
· Metals such as gold and silver are used in jewelry making. They are usually combined with copper to increase hardness.
Minerals form in several ways.
· What types of minerals form in an area depends in part on which elements are present there. Temperature and pressure also affect which minerals form.
· Minerals form when:
- Water evaporates- When salt water evaporates the atoms that form halite join to form crystals. Gypsum also forms when water evaporates.
- Hot water cools- As hot water within the crust moves through rocks, it can dissolve minerals. When it cools, the minerals separate from water and become solid again. Gold and lead are formed from this process.
- Molten rock cools- Many minerals grow from magma. Magma contains all the types of atoms that are found in minerals. As magma cools, minerals form. Minerals also form when lava cools. Quartz is a mineral that forms from molten rock cooling.
- Heat and pressure cause changes- Heat and pressure within Earth cause new minerals to form as bonds between atoms break and join again. Carbon forms graphite, which is used in pencils, in this way.
- Organisms produce minerals- A few minerals are formed from living things. Oysters and clams produce calcite. Your body produces one of the main minerals in your bones and teeth—apatite.
Many minerals are mined.
· Before minerals can be used to make products, they must be removed from the ground. Some are near the surface, others are deep within. Some are found at a wide range of depths.
· Minerals are only mined if the rock contains enough ore.
· Minerals at or near the surface are collected by surface mining.
· Gold is very dense. It can build up in riverbeds and be carried by water. In a process called panning, miners use a pan to wash away unwanted minerals that are less dense.
· Strip mining is another method of surface mining in which miners strip away plants, soil and unwanted rocks from the Earth’s surface with special machinery.
· Open-pit mining is similar to strip mining. They go one step further, though, and use explosives to remove underlying rock. Copper and iron ores are mined in this way.
· When ores lie deep beneath the Earth’s surface, deep mining is utilized. Here miners dig a deep passage and then blast, drill or cut the ore. Deep mining is a very dangerous endeavor.
2.3 Review Questions (pg. 66)
1. Give two examples of the use of minerals in industry and two examples of the use of minerals in the arts.
2. What are the five ways in which minerals form?
3. What is required for rocks to be considered ores?
4. Would an ore at the Earth’s surface or an ore deep underground be more expensive to mine? Explain.
5. The mineral quartz has been used as a gemstone for thousands of years. What minerals could jewelry makers use to grind and polish quartz?