Transcript What is a Mineral?

What is a Mineral
pages 103-114
the building blocks of rocks
Minerals of Earth’s Crust
Mineral definition
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A mineral is a natural, usually inorganic
solid that has a characteristic chemical
composition, an orderly internal structure,
and a characteristic set of physical
properties.
Five characteristics
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naturally formed
inorganic
crystalline structure
solid
definite chemical composition
Naturally Formed
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Not man made, naturally occurring
Inorganic
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Organic means living so, this means
non-living
Crystalline structure
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The atoms are arranged in a pattern
that repeats over and over
Solid
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Definite volume and shape
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Not a liquid or gas
Definite Chemical Composition
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Its chemical composition may be
written down in a formula and is fairly
consistent or within a range
Example:
Halite (salt) NaCl
Galena (lead) Pb
Kinds of Minerals
More than 4,000 have been identified
 Fewer than 20 are common
 These are called rock-forming
minerals
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These ten
make up 90% of the crust
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Quartz
Orthoclase
Plagioclase
Muscovite
Biotite
Calcite
Dolomite
Halite
Gypsum
Ferromagnesian minerals
Ferromagnesian mineral
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Contain iron and magnesium
Two groups of minerals
Based on chemical composition
 Silicates
 Non-silicates--
Silicates—contain a combination of
 Silicon,
Si
 Oxygen, O
 Silicates make up more than 90%
of the Earth’s crust
Six Kinds of
Silicate Mineral Arrangements
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Isolated-do not link with other silicon or oxygen
atoms
Ring silicates—form rings by sharing oxygen
atoms
Single-chain silicates—form by sharing oxygen
atoms
Double chain silicates—form when two single
chains of tetrahedra bond to each other
Sheet silicates—form when each tetrahedron
shares three of its oxygen with other tetrahedra
Framework silicates—form when each
tetrahedron is bonded to four other tetrahedra
Nonsilicates
5 groups
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Carbonates
Halides
Native elements
Oxides
Sulfates
Sulfides
From page 105
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Write name of group
Composition do not
fail to write it all!
An example of a
mineral form each
group
Silica tetrahedra Lab Part 1
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Materials
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Toothpicks
Marshmallows
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Page 106
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Silicon tetrahedra lab part 2
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Cut out the tetrahedron
Arrange tetrahedron to form the six kinds
of silicate mineral arrangements (page
107)
Glue onto construction paper and label
structures
Mineral Identification
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Minerals are identified using their
physical properties.
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These include crystal form, hardness,
cleavage, luster, color, streak, and
specific gravity.
Crystal Form
Crystal form is caused by the orderly
internal arrangement of atoms
Quartz is the most commonly identified
by its crystal form
Two or more minerals that
have the same chemical
composition but different
crystal structures are called
polymorphs.
Hardness
Moh's Scale of Hardness
10
9
8
7
6
5
4
3
2
1
Diamond
Corundum
Topaz
Quartz
Feldspar
Apatite
Fluorite
Calcite
Gypsum
Talc
Hardness
of some common objects
2.5
3
5
5.5
7
Fingernail
Penny
Pocket Knife
Window Glass
Steel File
Cleavage
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The tendency of a mineral to break
along planes of weakness.
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Some have good cleavage, some poor.
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It depends on the crystal structure and
chemical bonds: the stronger the bond
the poorer the cleavage.
Fracture
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A break that is not along a cleavage
plane
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Common type is conchoidal fracture.
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Ex. Quartz
Broken glass appearance
Or can be splinters and fibers--asbestos
Luster
The way light reflects from the
surface
I. Metallic
II. Nonmetallic
a.
b.
c.
d.
Greasy
Silky
Pearly
Glassy
Color
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Color is good for a few minerals like
copper and turquoise, but is not a very
reliable means of identification.
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The majority of minerals appear in a
variety of colors. Impurities can change
the color.
Streak
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The color of the powdered mineral
Much more reliable.
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Drag the mineral across a streak plate.
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Hematite--reddish brown to black,
but usually reddish brown
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Limonite--yellowish brown
Specific Gravity
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A mineral’s density
d=m/v
Density = mass/volume
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Densities are compared to an equal volume
of water
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There is no unit
Quartz -- 2.65
Silver -- 10.5
Gold -- 19.3
Other Tests
 Taste
Halite--NaCl has a salty taste
Fizz
 If
a mineral contains CO3 it
will effervesce (fizz) when
you drop dilute HCl
(hydrochloric acid) on it.
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Ex. Calcite CaCO3
Feel
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Talc has a soapy feel
Smell
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Sulfur has a rotten egg smell
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Kaolinite has an earthy smell
Etc
Writes on paper--graphite
 Rusty look—limonite
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How to Identify Minerals
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This film reviews some of the tests
covered in your notes.
Mineral Lab
Test each of the minerals to
determine their physical properties,
and then identify them using the
chart.
 Fill this in well.
 This is a major grade.
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