Mineral Characteristics

1
Mineral Characteristics
What is a mineral?

• A mineral is a naturally occurring, inorganic
  solid with a specific chemical composition and a
  definite crystalline structure.

Naturally Occurring and Inorganic

• That minerals are naturally occurring means that
  they are formed by natural processes.
• All minerals are inorganic, meaning that they
  arent alive and never were alive during any part
  of their existence.

2
Mineral Characteristics
What is a mineral?

• Definite Crystalline Structure

• A crystal is is a solid in which the atoms or
  molecules are arranged in a definite pattern that
  is repeated over and over again. There are 6
  crystal shapes.

3
What is a mineral?
What is a mineral?

• Earths crust is composed of about 3000 minerals.
  

• Only about 30 minerals are common in Earths
  crust.

4
Minerals Formation
What is a mineral?

• Minerals form by four major processes
• Magma hardening
• Changes in pressure
• Changes in temperature
• Formation of hydrothermal solutions

5
Mineral Groups
What is a mineral?
6
Mineral Groups
What is a mineral?

• Silicates

• Silicates are minerals that contain silicon and
  oxygen, and usually one or more other elements.

• Silicates make up approximately 96 percent of the
  minerals found in Earths crust.
• The most common minerals, feldspar and quartz,
  are silicates.
• Ex Olivine is Mg2SiO4

7
Mineral Groups
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.
• Ex Calcite is CaCO3

8
Mineral Groups
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.

9
Mineral Groups
What is a mineral?

• Sulfates and Sulfides

• Sulfates such as anhydrite (CaSO4) are composed
  of elements with the sulfate compound SO4.
• Sulfides such as pyrite (FeS2) are compounds of
  sulfur and one or more elements.

10
Halides

• Halides such as halite (NaCl) are made up of
  chloride or fluoride along with calcium, sodium,
  or potassium.

11
Mineral Groups

• Native elements
• A native element such as silver (Ag) or copper
  (Cu) is made up of one element only.

12
Mineral Groups
What is a mineral?
13
Section Assessment
What is a mineral?

• 1. Match the following terms with their
  definitions.
• ___ mineral
• ___ crystal
• ___ magma
• ___ silicate

A. minerals that contain silicon and oxygen, and
usually one or more other elements B. a naturally
occurring, inorganic solid with a specific
chemical composition and definite crystalline
structure C. a solid in which the atoms are
arranged in repeating patterns D. molten material
found beneath Earths surface
B C D A
14
Section Assessment
What is a mineral?

• 2. What are the two ways that minerals can form
  from a supersaturated solution?

Mineral crystals can precipitate, or drop out of
solution if the solution becomes supersaturated.
Minerals can also form when liquid evaporates
from a supersaturated solution leaving behind the
elements which may begin to arrange into
crystals.
15
Section Assessment
What is a mineral?

• 3. Identify whether the following statements are
  true or false.

_______ There are about 30 common minerals in
Earths crust. _______ Slowly cooling magma
produces small crystals. _______ Coal is a
mineral. _______ Silicates are the most common
minerals on Earth. _______ Well-defined crystal
shapes are rare.
true false false true true
16
End of Section 1
17
Mineral Identification
Identifying Minerals

• Geologists rely on several relatively simple
  tests to identify minerals.

• These tests 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.

18
Mineral Properties

• Minerals have certain physical properties that
  can be used to identify them.
• -color -luster
• -hardness -streak
• -density -crystal shape
• -breakage -special properties

19
Mineral Identification
Identifying Minerals

• Color

• - Color is easy to see but not always reliable
  because
• Many minerals have same color
• Color can change.

20
Mineral Identification
Identifying Minerals

• Streak

Streak is the color of powder scraped off a
mineral when it is rubbed against a rough hard
surface. You can find streak by rubbing a mineral
across a piece of unglazed porcelain tile (a
streak plate).
21
Mineral Identification
Identifying Minerals

• Luster

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

• Metallic is shiny like a metal.
• Nonmetallic luster might be described as dull,
  pearly, waxy, or silky.

22
Crystal Structure

• A mineral may be identified by its crystal
  structure, one of the six previously mentioned.

23
Mineral Identification
Identifying Minerals

• Hardness

• Hardness is a measure of how easily a mineral can
  be scratched.

• We use Moh's hardness scale. We use different
  tools to find the hardness- fingernail, penny,
  nail, glass plate and streak plate. Diamond, the
  hardest, is a10. Talc, the softest, is a 1.
• Any mineral with a greater hardness than another
  mineral will scratch that softer mineral.

24
Mineral Identification
Identifying Minerals

• Hardness

25
Mineral Identification
Identifying Minerals

• Cleavage

• 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.

26
Fracture

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

27
Mineral Identification
Identifying Minerals

• Density and Specific Gravity

• Differences in weight are the result of
  differences in density, which is defined as mass
  per unit of volume.
• Density is expressed as a ratio of the mass of a
  substance divided by its volume, or D M/V.
• Density reflects the atomic weight and structure
  of a mineral.
• 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.

28
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.
• Magnetite, an iron ore, is naturally magnetic.

29
Special Properties

• Calcite (CaCO3) fizzes when it comes into contact
  with hydrochloric acid (HCl).

30
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.

31
Mineral Uses
Identifying Minerals

• Ores

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

• Examples of ores include Hematite, which contains
  the element iron and bauxite, which contains the
  element aluminum.

32
Mineral Uses
Identifying Minerals

• Mines

• Ores are removed by underground mining or from
  large, open-pit mines.
• When a mine is excavated, unwanted rock and dirt,
  known as waste material, are dug up along with
  ore.
• If the cost of separating the waste material
  becomes higher than the value of the ore itself,
  then the mineral will no longer be classified as
  an ore because it would no longer be economical
  to mine it.
• The classification of a mineral as an ore may
  also change if the supply of or demand for that
  mineral changes.

33
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.

34
Section Assessment
Identifying Minerals

• 1. Match the following terms with their
  definitions.
• ___ streak
• ___ hardness
• ___ cleavage
• ___ fracture

A. the ability to break with arc-like, rough, or
jagged edges B. the ability to split relatively
easily along one or more flat planes C. the
color of a mineral when it is broken up and
powdered D. a measure of how easily a mineral can
be scratched
C D B A
35
Section Assessment
Identifying Minerals

• 2. How would an oversupply of ore possibly change
  the minerals classification as an ore?

If an ore is over supplied, it could drive down
prices for the ore. This may create a situation
in which it would no longer be economical to mine
material, thus the material would no longer be
classified as an ore.
36
Section Assessment
Identifying Minerals

• 3. What is specific gravity?

Specific gravity is the ratio of the weight of a
substance to the weight of an equal volume of
water at 4ºC. It is a common measure of density
used by geologists.
37
End of Section 2
38
Chapter Resources Menu
Chapter Resources Menu

• Study Guide
• Section 4.1
• Section 4.2
• Chapter Assessment
• Image Bank

39
Section 4.1 Main Ideas
Section 4.1 Study Guide

• A mineral is a naturally occurring, inorganic
  solid with a specific chemical composition and a
  definite crystalline structure. There are at
  least 3000 known minerals in Earths crust.

• A crystal is a solid in which the atoms are
  arranged in repeating patterns. The six main
  crystal systems are cubic, tetragonal, hexagonal,
  orthorhombic, monoclinic, and triclinic.
• Minerals form from magma or from supersaturated
  solution. Most minerals are formed from the eight
  most common elements in Earths crust.

40
Section 4.1 Main Ideas
Section 4.1 Study Guide

• Oxygen readily combines with other elements to
  form a diverse group of minerals, including
  silicates, carbonates, and oxides. A silica
  tetrahedron is a three-dimensional shape
  structured like a pyramid. In a silica
  tetrahedron one silicon atom attaches to four
  oxygen atoms.

• Other major mineral groups include sulfides,
  sulfates, halides, and native elements. Native
  elements such as silver or copper are made of one
  element only.

41
Section 4.2 Main Ideas
Section 4.2 Study Guide

• Minerals can be identified based on their
  physical and chemical properties. The most
  reliable way to identify a mineral is by using a
  combination of several tests.

• A minerals color is generally the result of
  trace elements within the mineral. Texture
  describes how a mineral feels, and luster
  describes how a mineral reflects light. Cleavage
  and fracture describe how minerals break.
• A minerals streak, hardness, and density are
  reliable methods of identification. Special
  properties of minerals such as magnetism also can
  be used for identification purposes.

42
Section 4.2 Main Ideas
Section 4.2 Study Guide

• An ore contains a useful substance that can be
  mined at a profit. If the cost of mining the ore
  becomes higher than the value of the ore, then
  the mineral is no longer classified as an ore.
  The classification of a mineral as an ore may
  also change if the supply of or demand for the
  mineral changes.

• Gems are valuable minerals that are prized for
  their rarity and beauty. Trace elements can make
  one variety of a mineral more valuable than other
  varieties of the same mineral.

43
Multiple Choice
Chapter Assessment

• 1. What special property can be used to help
  identify the mineral sphalerite?
• a. It fizzles when it comes in contact with HCl.
• b. It exhibits double refraction.
• c. A rotten-egg odor is produced during a
  streak test.
• d. It is naturally magnetic.

Calcite reacts with HCl. Iceland spar and zircon
exhibit double refraction when light is passed
through them. Magnetite is naturally magnetic.
44
Multiple Choice
Chapter Assessment

• 2. A mineral with a metallic luster could be
  described as ___.
• a. silky c. pearly
• b. shiny d. waxy

Silky, pearly, and waxy can all be used to
describe nonmetallic luster.
45
Multiple Choice
Chapter Assessment

• 3. Which ore is a source of iron?
• a. bauxite c. zircon
• b. rutile d. hematite

Bauxite is an aluminum ore. The ore rutile is a
source of titanium. Zircon contains no iron.
46
Multiple Choice
Chapter Assessment

• 4. A silica tetrahedron contains ___ oxygen
  atoms.
• a. one c. three
• b. two d. four

A silica tetrahedron is made up of one silicon
atom bonded to four oxygen atoms.
47
Multiple Choice
Chapter Assessment

• 5. Which of the following is an example of native
  element mineral?
• a. halite c. copper
• b. pyrite d. anhydrite

A native element mineral is made up of only one
element. Halite (NaCl), pyrite (FeS2), and
anhydrite (CaSO4) all contain more than one
element.
48
Short Answer
Chapter Assessment

• 6. Why are crystals that form in well-defined
  shaped fairly rare?

Most crystals form in restricted space.
49
Short Answer
Chapter Assessment

• 7. What are the characteristics of minerals?

To be a mineral, a material must be a naturally
occurring, inorganic solid with a specific
chemical composition, and a definite crystalline
structure.
50
True or False
Chapter Assessment

• 8. Identify whether the following statements are
  true or false.
• ______ About 90 known elements occur naturally
  in Earths crust.
• ______ Oxides are compounds of oxygen and
  another gas.
• ______ Pyrite has a hexagonal crystal system.
• ______ Ores must be mined at a profit.
• ______ Rubies are more valuable than diamonds.

true false false true true
51
Chapter 4 Images
Image Bank
52
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