1. Mineral Resources: Why bother?

3. Mineral resources Mineral resources are:
minerals or rocks mined from the earth and used in the products we use daily.
Coal, oil and natural gas are also mined, but these energy resources will be considered separately. 3

4. The use of minerals and rocks in products
Sometimes actual minerals and rocks are used in products, or to make things. The rock granite is mined to make counter tops, and the mineral halite is mined, crushed, and sold as table salt.
Other times, minerals and brines are processed to extract one specific element, and these individual elements are often called mineral commodities. For example, the commodity aluminum is extracted from the rock bauxite, which contains aluminum-bearing minerals like gibbsite.
The process of extracting the desired mineral or element from an ore is called beneficiation.

5. Minerals Minerals are: solid
inorganic (or identical to an inorganic mineral)
natural (or made in a way that mimics nature)
chemically homogeneous – (the mineral contains the same chemicals throughout)
crystalline (the atoms in a mineral are arranged in an orderly and repeating pattern)

6. Examples of minerals Mineral Quartz Hematite Diamond Halite
Chemical formula
SiO2
Fe2O3 C
NaCl
Elements in these minerals
Si = silicon, O = oxygen
(two oxygen atoms for every one silicon atom)
Fe = iron, O = oxygen (two iron atoms for every three oxygen atoms)
C = carbon
Na = sodium, Cl = chlorine
Crystal structures Na Cl
Crystal structure models from: Si O Fe O C

7. NOT minerals
The "minerals" in these “vitamins and minerals” are not real minerals. These are elements that may have been extracted from minerals.

8. Common elements and common minerals
Minerals are comprised of elements.
Eight elements make up the majority of Earth's crust and mantle:
What’s within the crust (by mass)
Elements in the crust
Mass%
Oxygen (o)
46.6%
Silicon (Si)
27.72%
Aluminum (Al)
8.13%
Iron (Fe)
5.00%
Calcium (Ca)
3.63%
Sodium (Na)
2.83%
Potassium (K)
2.59%
Magnesium (Mg)
2.09%
Common metals (Al,Fe,Ca,
Na, K,
Mg)
All others
Oxygen
Silicon

9. Common elements and common minerals
These elements can combine in a variety of ways to make different minerals.
Most minerals contain silicon and oxygen (plus other elements). These minerals are called silicate minerals. Fe Al Si O
Crystal structure of almandine garnet (Fe3 Al2 Si3 O12 ) containing iron and aluminum in addition to silicon and oxygen.

10. Common elements and common minerals Why do we care about this?
Sustainability: The eight elements just listed are the most plentiful. Other elements are more rare; we find them less frequently and have a lower overall supply of them.
Ease of use: Silicate minerals tend to be refractory; they have high melting points and low solubilities, so they hold onto the elements within them.
If we want the element in the mineral (and not the mineral itself), then we seek non-silicate minerals that contain the element, because it is easier (fewer resources are needed) to extract those elements from the mineral.

11. For example, the silicate mineral fayalite (Fe2SiO4) contains iron (Fe). However, it has a melting point of 1205oC, and so it will take a lot of energy if we want to extract iron from fayalite. It is easier to extract iron from hematite (Fe2O3), which is a non-silicate mineral.
Fayalite. Not an economic source for iron, though they contain iron
Hematite. Iron is commonly extracted from this mineral.

12. Mineral properties
A mineral's chemical and crystalline nature gives them properties that make them useful.
These properties also must be considered when determining how to best mine, process, and dispose of the mineral and mine waste.

13. Sulfur can be found as a mineral (native sulfur, S)
Mineral properties: Chemistry
The elements within minerals give them distinct and useful properties.
For example:
sulfur allows gunpowder to ignite at a lower temperature, and provides fuel for the fire.
Sulfur can be found as a mineral (native sulfur, S)
Sulfur can also exist as an element within other minerals like pyrite (FeS).

14. Mineral properties: Chemistry
For example:
Aluminum metal is very lightweight but strong.
Aluminum alloys were extensively used for constructing Apollo 16 whose Command and Service Module (CSM) "Casper" is shown here
Aluminum does not form a mineral on its own, but is beneficiated from the minerals gibbsite and bohemite.
Photo from NASA (

15. Crystal structure for graphite Crystal structure for diamond
Mineral properties: Hardness
A mineral's hardness is determined by:
The crystalline nature of that mineral,
The type and strength of bonds that hold the atoms together, and,
The nature of the repeating pattern
Both graphite and diamond are made up of the same element, carbon (C). However, diamond is much harder than graphite.
Crystal structure for graphite
Crystal structure for diamond
Carbon
Carbon
Crystal structure models from:

16. Mineral properties: Hardness
For example:
Very hard minerals (like diamond, corundum, and garnet) are useful as abrasives. Saw blades impregnated with diamonds can cut rock, and sandpaper is often made with garnet sand.
Almandine garnet crystals. Hardness of almandine garnet is 7-8
On the Moh’s scale of hardness
Talc (hardness=1 on the Moh’s scale of hardness) is used in baby powder because it is a very soft mineral.

17. Mineral properties: Color
Some minerals have distinct, and vibrant, colors. This makes them incredibly useful as pigments in paints, cosmetics, colored plastic, etc.
The rust red color of hematite (left) and rust yellow color of goethite (right) have long been used as a pigment.
Malachite’s green color has made it useful in paints

18. Mineral properties: Color
For example: The native people in Himba Village, Namibia, powder iron oxide minerals (like hematite and goethite) to color their skin and hair. Photo by Ansu John

19. Mineral properties: Specific gravity
Specific gravity is a relative density, determined both by a mineral's chemistry (minerals containing heavier elements will have higher specific gravities) and how closely together the atoms are packed.
Galena (PbS) contains the heavy element lead, giving it a high specific gravity

20. Mineral properties: Behavior of light in the crystal
The crystalline structure determines if and how light passes through a mineral. For example, light reflects inside of diamond, which gives diamond ring an exquisite sparkle. Other minerals (like rutile) are quite opaque, which makes titanium oxide (the chemical name of rutile) an important additive in things that need to be opaque, like paint. Some minerals are also useful in blocking other wavelengths of light; barite and lead (from the mineral galena) block X-rays, for example.
The crystalline structure of calcite (Iceland spar variety) can split light rays passing through it, making the horizontal lines seen through the calcite crystal appear to double up in this photo.
Iceland Spar crystals are used in polarizing microscopes and telescopes because of this property.

21. Mineral properties: Luster
Luster describes how light interacts with the surface of a mineral.
For example, the mineral hematite can have both metallic or nonmetallic luster; hematite with metallic luster (photo on left) is used to make jewelry.

22. Mineral properties: Crystal shape and cleavage
These are determined by the nature of the crystalline structure. The sheet-like cleavage of muscovite allows it to be broken into tiny pieces of glitter.
Muscovite’s cleavage causes it to break into sheets.

23. Mineral properties: Solubility
Different minerals dissolve differently depending on their crystalline structure (the type of bonds) and chemistry. When a mineral dissolves, it breaks into the ions that it contains. Some dissolve quickly in water (or acidic or alkali solutions), whereas others are very stable.
For example, people eat tablets made of calcite; that calcite dissolves in the stomach, neutralizing some of the acid and reducing heartburn
TUMS® tablet dissolving in acidic water releasing bubbles of carbon dioxide.

24. Mineral properties: Solubility
For some applications, an insoluble mineral is preferred. For example, the Eads Bridge that crosses the Mississippi River is faced with rock made of insoluble minerals below the water line, whereas more decorative limestone (made of the more soluble mineral calcite) faces the support above the water line. If a mineral is being mined from the element it contains, then it will be easier to extract that element from a soluble mineral.

25. Mineral properties: Magnetism
The chemistry of certain minerals allows them to store an applied magnetic field. For example, magnetic minerals in a hard drive can be programmed to store information.
A bar magnet hanging from a sample of magnetite. Magnetite is an iron oxide (Fe3O4), and is naturally magnetic.

26. Mineral properties: Electrical conductivity
Electrical conductivity is mainly determined by the presence of metallic bonds. Metals have these bonds, which is why metals are favored for wires.
Copper’s electrical conductivity and resistance to corrosion make it ideal for electric wiring.
Copper can be found as a pure metal (native copper, Cu)
Copper is often beneficiated from minerals like chalcopyrite (CuFeS2).

27. Mineral properties: Electrical conductivity
Minerals that have low electric conductivity will be used for insulators, which block and/or confine the electric current.
Image: FreeDigitalPhotos.net
Clay minerals such as kaolinite show very low electrical and thermal conductivity.
Ceramic insulators made from clay minerals are used for supporting electric power lines

28. Mineral properties: Thermal conductivity
Minerals can also be used to conduct or confine heat. Thermal conductivity is determined by both a mineral’s chemistry and crystalline structure
Clay minerals such as kaolinite show very low electrical and thermal conductivity.
Ceramic kitchen utensils made from clay minerals are used to confine the temperature of food and beverages

29. Mineral properties: Melting point
Different minerals melt at different temperatures. Minerals with high melting points are used for high temperature applications.
For example, the mineral graphite is used for lining furnaces and as crucibles for melting metals

30. Mineral properties: Response to stress
Different minerals/rocks behave differently under stress.
For example, while many minerals will shatter if hit with a hammer, gold is malleable. This allowed early people to easily shape it into ornaments.
Piezoelectricity is another property related to stress. An electric current is generated in piezoelectric minerals when a stress is applied. For example, a hammer hits a piezoelectric crystal, and this will generate a spark to ignite a cigarette lighter. The piezoelectricity of quartz allows it to be used to tell time (in quartz crystal watches), and piezoelectricity is also useful in transformers and motors.