Objectives

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Objectives
Luster Hardness Streak Cleavage Gem Ore

• Define a mineral
• Characterize how minerals are identified
• What are the different types of metals,
  non-metals, ores, and gems

Vocabulary
mineral
Luster Hardness Streak
Cleavage Gem Ore
crystal
Silicates
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Mineral Characteristics
What is a mineral?

• A mineral is
• naturally occurring
• formed by natural processes
• Inorganic
• Never living, never will be
• Solid
• Specific chemical composition
• Definite crystalline structure.
• Earths crust is composed of about 3000 minerals.
  

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Mineral Characteristics
What is a mineral?

• Definite Crystalline Structure

• Atoms in minerals are arranged in 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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Minerals form in 2 ways
What is a mineral?

• 1. From Magma
• Small crystals form from rapidly cooling magma.
• Large crystals form from slowly cooling magma.

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Minerals form in 2 ways
What is a mineral?

• 2. From Solution

• If a solution becomes supersaturated, or
  overfilled, with another substance, mineral
  crystals may begin to precipitate, or drop out of
  solution.
• When liquid evaporates the element remains and
  begins crystallize.

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Mineral Groups
What is a mineral?

• About 30 minerals are common in Earths crust.

• Called rock-forming minerals because they make
  up most of the crust.
• The vast majority of minerals are made up of the
  eight most common elements.

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Mineral Groups
What is a mineral?

• Most minerals are formed from the eight most
  common elements in Earths crust.

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Mineral Groups
What is a mineral?

• 1. Silicates

• Silicates contain silicon, oxygen, and one or
  more other elements.

• make up 96 percent of minerals in Earths crust.
• Most common feldspar and quartz

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Mineral Groups
What is a mineral?

• 2. Carbonates

• composed of one or more metallic elements with
  the carbonate compound CO3.
• the primary mineral found in rocks such as
  limestone and marble.

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Mineral Groups
What is a mineral?

• 3. Oxides

• 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 Identification
Identifying Minerals

• Geologists use several simple tests to identify
  minerals.

• Tests are based upon a minerals physical and
  chemical properties.

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Six Mineral Identification Tests
Identifying Minerals

• Color is one of the least reliable clues to a
  minerals identity
• trace elements or compounds within a mineral can
  change its color.

• 2. Luster is the way that a mineral reflects
  light
• is described as either metallic or nonmetallic.

• 3. Texture describes how a mineral feels.
• Texture can be described as smooth, rough,
  ragged, greasy, soapy, or glassy.

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Six Mineral Identification Tests
Identifying Minerals

• Streak is the color of the fine powder of a
  mineral obtained by scratching or rubbing against
  a hard white surface.
• Sometimes, a minerals streak does not match the
  minerals external color

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

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Mineral Identification
Identifying Minerals

• Hardness

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Six Mineral Identification Tests

• 6. Cleavage Fracture - Minerals break along
  planes where atomic bonding is weak.
• Cleavage some minerals split 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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Special Properties
Identifying Minerals

• Special properties of minerals also can be used
  for identification purposes.

• A type of calcite called Iceland spar causes
  light to be bent in two directions, a process
  known as double refraction, 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

• Ores

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

• - If the cost of separating waste material from
  ore becomes higher than the value of the ore
  itself, then the mineral is no longer considered
  to be an ore.
• The classification of a mineral as an ore may
  also change if the supply of or demand for that
  mineral changes.

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Gems
Identifying Minerals

• Gems are valuable minerals that are prized for
  their rarity and beauty.

• Gems such as rubies, emeralds, and diamonds are
  cut, polished, and used for jewelry.
• In some cases, the presence of trace elements can
  make one variety of a mineral more colorful and
  thus more prized than other varieties of the same
  mineral.