What is a mineral?

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What is a mineral?
What is a mineral?

• Earths crust is composed of about 3000 minerals.
  

• Minerals play important roles in forming rocks
  and in shaping Earths surface.

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What is a mineral?
Naturally Occurring and Inorganic

• Naturally occurring means that they are formed by
  natural processes.
• Inorganic means that they arent alive and never
  were alive

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What is a mineral?

• Solids with Specific Compositions

• All minerals are solids with definite shapes and
  volumes.
• Each type of mineral has a chemical composition
  unique to that mineral.

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What is a mineral?

• Definite Crystalline Structure

• The atoms in minerals are arranged in regular
  geometric patterns that are repeated again and
  again.
• A crystal is a solid in which the atoms are
  arranged in repeating patterns.

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What is a mineral?

• Definite Crystalline Structure

• At times and fairly rare, a mineral will form in
  an open space and grow into one large crystal,
  possibly taking the shape of one of the six major
  crystal systems.

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What is a mineral?

• Minerals can form from the cooling of magma.

• Small crystals form from rapidly cooling magma
  and large crystals form from slowly cooling
  magma.

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Minerals from Solution (Our Lab in D15)
What is a mineral?

• If a solution becomes supersaturated, or
  overfilled, with another substance, mineral
  crystals may begin to precipitate, or drop out of
  solution.

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Mineral Groups
What is a mineral?

• About 30 minerals are common in Earths crust.

• The vast majority of minerals are made up of the
  eight most common elements.

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Mineral Groups- Silicates
What is a mineral?

• Contain Silicon and Oxygen.

• Silicates make up 96 percent of the minerals
  found in Earths crust.
• The most common minerals, feldspar and quartz,
  are silicates.

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What is a mineral?

• Carbonates

• Carbonates are minerals composed of one or more
  metallic elements with the carbonate compound
  CO3.
• Carbonates are the primary minerals found in
  rocks such as limestone, coquina, and marble.

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What is a mineral?

• Oxides

• Oxides are compounds of oxygen and a metal.
• Hematite (Fe2O3) and magnetite (Fe3O4) are common
  iron oxides and good sources of iron.

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Mineral Groups
What is a mineral?
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Mineral Identification
Identifying Minerals

• Geologists have simple tests to identify minerals.

• They are based upon a minerals physical and
  chemical properties.
• It is usually best to use a combination of tests
  rather than just one to identify minerals.

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Identifying Minerals

• Color is sometimes caused by the presence of
  trace elements or compounds within a mineral.
• Color is one of the least reliable clues to a
  minerals identity.

• Color

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Identifying Minerals

• Luster

• Luster is the way that a mineral reflects light
  from its surface.

• Luster is either metallic or nonmetallic.
• Metallic luster is a shiny surface that reflect
  light like the chrome trim on cars.
• Nonmetallic luster might be described as dull,
  pearly, waxy, or silky.

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Identifying Minerals

• Texture

• Texture describes how a mineral feels to the
  touch.
• The texture of a mineral might be described as
  smooth, rough, ragged, greasy, soapy, or glassy.

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Identifying Minerals

• Streak

• Streak is the color of a mineral when it is
  broken up and powdered.

• Sometimes, a minerals streak does not match the
  minerals external color.
• A minerals streak rarely changes.

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Identifying Minerals

• Hardness

• Hardness is one of the most useful and reliable
  tests for identifying minerals.
• Hardness is a measure of how easily a mineral can
  be scratched.

• German geologist Friedrich Mohs developed a scale
  to compare unknown minerals with common minerals.
• Any mineral with a greater hardness than another
  mineral will scratch that softer mineral.

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Identifying Minerals

• Hardness

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Identifying Minerals

• Cleavage and Fracture

• Minerals break along planes where atomic bonding
  is weak.
• Cleavage is the ability of a mineral to split
  relatively easily and evenly along one or more
  flat planes.

• Fracture is the ability of minerals to break with
  arclike, rough, or jagged edges.

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Identifying Minerals

• Density and Specific Gravity

• Density is expressed as a ratio of the mass of a
  substance divided by its volume, or D M/V.
• The most common measure of density used by
  geologists is specific gravity.
• Specific gravity is the ratio of the weight of a
  substance to the weight of an equal volume of
  water at 4C.

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Special Properties
Identifying Minerals

• Special properties can be used for identification
  purposes.

• A type of calcite called Iceland spar causes
  light to be bent in two directions when it passes
  through the mineral.
• Calcite (CaCO3) fizzes when it comes into contact
  with hydrochloric acid (HCl).
• Magnetite, an iron ore, is naturally magnetic.
• The mineral sphalerite produces a distinctive
  rotten-egg odor when it is rubbed vigorously
  across a streak plate.

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Mineral Uses
Identifying Minerals

• Minerals are virtually everywhere.

• They are used to make computers, cars,
  televisions, desks, roads, buildings, jewelry,
  beds, paints, sports equipment, and medicines,
  just to name a few uses.

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Mineral Uses
Identifying Minerals
Gems

• Ores

• An ore is a mineral that contains a useful
  substance that can be mined at a profit.

• Examples of ores include iron and lead.

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Classifying Minerals