EPS 038: Lab
Minerals
Why study Minerals?
• minerals can be beautiful and valuable (gems)
Why study Minerals?
• minerals can be beautiful and valuable (gems)
• minerals are useful and economically important
Why study Minerals?
• minerals can be beautiful and valuable (gems)
• minerals are useful and economically important
• minerals are the building blocks of the solid planets
Definition of a Mineral
A mineral is a homogeneous, naturally
occurring, solid, inorganic substance, with a
definable chemical composition and an
internal structure
characterized by an
orderly (crystalline) arrangement of atoms.
Definition of a Mineral
A mineral is a homogeneous, naturally
occurring, solid, inorganic substance, with a
definable chemical composition and an
internal structure
characterized by an
orderly (crystalline) arrangement of atoms.
Homogeneous materials are the same through and
through. If you smash a mineral, you get fragments of
the same mineral.
Rocks are aggregates of different minerals.
Definition of a Mineral
A mineral is a homogeneous, naturally
occurring, solid, inorganic substance, with a
definable chemical composition and an
internal structure
characterized by an
orderly (crystalline) arrangement of atoms.
True minerals form by natural processes.
However, synthetic minerals can be manufactured by
scientists or industries (synthetic diamonds).
Definition of a Mineral
A mineral is a homogeneous, naturally
occurring, solid, inorganic substance, with a
definable chemical composition and an
internal structure
characterized by an
orderly (crystalline) arrangement of atoms.
A solid is a form of matter that can maintain its own
shape, and will not conform to the shape of its container.
Liquids (water or oil) or gases (air) are not minerals.
Definition of a Mineral
A mineral is a homogeneous, naturally
occurring, solid, inorganic substance, with a
definable chemical composition and an
internal structure
characterized by an
orderly (crystalline) arrangement of atoms.
Minerals are not made of organic compounds.
Examples of organic compounds are fat, oil, plastic,
protein, alcohol.
Definition of a Mineral
A mineral is a homogeneous, naturally
occurring, solid, inorganic substance, with a
definable chemical composition and an
internal structure
characterized by an
orderly (crystalline) arrangement of atoms.
It is possible to write a unique chemical formula for
every different mineral.
Quartz = SiO2
Calcite = CaCO3
Olivine = Mg2SiO4
Definition of a Mineral
A mineral is a homogeneous, naturally
occurring, solid, inorganic substance, with a
definable chemical composition and an
internal structure
characterized by an
orderly (crystalline) arrangement of atoms.
Atoms in a mineral are fixed in a specific pattern that repeats at
regular intervals to form a framework (a crystal structure).
Each mineral has its own specific crystal structure.
Learning to Identify Minerals
Minerals can be identified by two main types
of techniques.
1. In hand-sample.
2. By observation through a microscope or
analysis in a laboratory
In this lab, we will learn to identify minerals in hand-sample.
Properties used to Identify Minerals
in Hand-Sample
1.
2.
3.
4.
5.
Color
Streak
Luster
Hardness
Cleavage
Properties used to Identify Minerals
in Hand-Sample
1. Color
Color can be useful, BUT some minerals come in
many colors.
Examples: Quartz can be white, pink, yellow,
black or purple.
Olivine can be green, black or red.
Diamond can be colorless, pink, yellow,
purple.
Different colors can be caused by impurities.
Properties used to Identify Minerals
in Hand-Sample
2. Streak
A powdered sample of a mineral gives a color, called
its streak, which is usually more diagnostic than the
color of the specimen itself.
Streak can be determined by scraping the edge of a
mineral on a ceramic plate.
Example:
Hematite has a red-brown streak, even
though the mineral can be silver, red or
brown.
Properties used to Identify Minerals
in Hand-Sample
3. Luster
The quality and intensity of light reflected from the
surface of a mineral is called its luster.
Luster is either metallic (shiny, highly reflective) or
non-metallic .
Examples: Pyrite and galena have metallic luster.
Most silicate minerals have glassy luster.
Properties used to Identify Minerals
in Hand-Sample
4. Hardness
The property of hardness (“scratchability”) of a
mineral can be a reliable indicator of its identity.
Moh’s hardness scale of standard minerals is used to
determine hardness.
Moh’s Hardness Scale
1. Talc
2. Gypsum
fingernail
3. Calcite
copper penny
4. Fluorite
5. Apatite
steel knife, glass
6. Feldspar
7. Quartz
8. Topaz
9. Corundum (ruby)
10. Diamond
Properties used to Identify Minerals
in Hand-Sample
5. Cleavage
Cleavage is the tendency of a mineral to break along
planes that reflect their internal crystal structure.
micas: one cleavage plane
Properties used to Identify Minerals
in Hand-Sample
5. Cleavage
Cleavage is the tendency of a mineral to break along
planes that reflect their internal crystal structure.
feldspar: two cleavage planes
Properties used to Identify Minerals
in Hand-Sample
5. Cleavage
Cleavage is the tendency of a mineral to break along
planes that reflect their internal crystal structure.
halite: three cleavage planes (cubes)
Properties used to Identify Minerals
in Hand-Sample
5. Cleavage
Cleavage is the tendency of a mineral to break along
planes that reflect their internal crystal structure.
calcite: three cleavage planes (but not cubes)
Properties used to Identify Minerals
in Hand-Sample
5. Cleavage
Cleavage planes should not be confused with crystal
faces, which reflect how a mineral has grown.
cleavage
crystal
faces
Properties used to Identify Minerals
in Hand-Sample
5. Cleavage
Cleavage planes should not be confused with crystal
faces, which reflect how a mineral has grown.
Quartz commonly shows crystal faces, but not cleavage.
Properties used to Identify Minerals
in Hand-Sample
6. Special Properties
Some minerals have special properties.
Examples: Magnetite is magnetic.
Calcite dissolves (or fizzes) in acid.
Classes of Minerals
(see p. 121 of textbook)
Silicates
• based on -SiO4 group
• most common rock-forming minerals
• examples - olivine, pyroxene, quartz, feldspar, micas.
olivine
feldspar
quartz
Classes of Minerals
(see p. 121 of textbook)
Carbonates
• based on -CO3 molecule
• most common in sedimentary rocks
• examples - calcite, dolomite.
calcite
Classes of Minerals
(see p. 121 of textbook)
Sulfates
• based on -SO4 molecule
• most common in sedimentary rocks
• example - gypsum.
gypsum
Classes of Minerals
(see p. 121 of textbook)
Sulfides
• based on -S
• common ore minerals
• examples - galena (PbS); pyrite (FeS2)
galena
pyrite
Classes of Minerals
(see p. 121 of textbook)
Oxides
• based on -O
• common ore minerals
• examples - magnetite (Fe3O4); hematite (Fe2O3)
magnetite
hematite
Classes of Minerals
(see p. 121 of textbook)
Halides
• based on -F or -Cl
• examples - halite (NaCl - SALT); fluorite (CaF2)
halite
fluorite
Classes of Minerals
(see p. 121 of textbook)
Native Metals
• single element
• examples - gold; copper; graphite (C), diamond (C)
gold
copper
Classes of Minerals
(see p. 121 of textbook)
Native Metals
• single element
• examples - gold; copper; graphite (C), diamond (C)
graphite
diamond
Mineral Quiz
Section D50A: Thursday June 15
Section D51A: Monday June 19