Minerals Download

Transcript
Building a House Out of Minerals
A roof is a barrier to snow
and rain. What mineral is used in clay
singles to cover the plywood sheets
on the roof?
Cement is used for the foundation and chimney
of a house. Cement contains this mineral
which is a source of calcium.
___________________
___________________
Exterior walls can be made of
things such as aluminum or steel
siding or brick. What is one mineral
that could be found in aluminum
siding?
Interior walls shape the rooms in a
house. The wallboard covers the
walls and is soft so that holes can
be drilled in it for outlets and nails
can be used to hang pictures. What
mineral is wallboard made of?
___________________
___________________
Metal pipes are commonly used to
carry fresh water into the house. In
the 1950’s a poisonous mineral
was used in plumbing, what was it?
___________________
Windows let in visible light and
allow us to see outside. What clear
mineral is used to make window
glass?
Electrical wiring conducts electricity
most wiring in made of metal. What
mineral is often used for wiring?
___________________
Word Bank: Aluminum, Lead, Gypsum, Copper, Quartz, Illite (clay), Calcite
___________________
 Minerals versus
Rocks
 Composition and
Structure of Minerals
 Properties of
Minerals
The Star of Bombay
 Mineral Groups
182-carat star sapphire
 Mineral Resources
Minerals Versus Rocks
• A rock is an
aggregate of
minerals
• Minerals are
the building
blocks that
make up rocks
Varieties of Minerals
More than
3000
different
minerals
Quartz
Beryl (aquamarine)
Olivine (Peridot)
Native Copper
Definition of Mineral
•
•
•
•
•
Naturally occurring
Solid
Inorganic (never living)
Definite chemical composition
Orderly internal structure of atoms
Tetragonal
Cubic
Hexagonal
Graphite
Diamond
Chemical
formula:
C
Chemical formula:
C
How can 2 minerals with the same composition be
so different?
What’s the point here?
“Internal Arrangement of Atoms” controls most physical properties!
Mineral Formation
1. Cooling of magma-molten rock beneath
the earth’s surface
– if it cools fast small crystals
– if it cools slowly large crystals
2. Compounds dissolved in a liquid (water);
liquid evaporates & leaves behind
crystals
• Most minerals made up of only 8 elements these 8 elements make
up 98% of Earth’s crust
Relative abundance of the most common elements in
the Earth’s crust
Element
Approximate Percentage by
Weight
Oxygen (O)
46.6%
Silicon (Si)
Aluminum (Al)
Iron (Fe)
Calcium (Ca)
27.7%
8.1%
5.0%
3.6%
Sodium (Na)
Potassium (K)
2.8%
2.6%
Magnesium (Mg)
2.1%
All Others
1.7%
100%
Total
Mineral Groups
– Silicates: contains silicon + oxygen + one or
more other elements (Most common rock
forming minerals are silicates)
– Carbonates: 1 carbon + 3 oxygen + other
elements
– Oxides: 2 oxygen + other elements
– Sulfides: sulfur + other elements
– Sulfates: 1 sulfur + 4 oxygen + other elements
– Halides: chlorine, fluorine, bromine, or Iodine
+ other elements
– Native elements: elements that are
uncombined
Silicates
Quartz
SiO2
Mica
KAl2(AlSi3O10)(OH,F,Cl)2
Can you find the “silica” ?
Silica Structure
4 oxygen atoms for
every 1 silicon atom
Carbonates
Calcite
Mineral Identification
•
•
•
•
•
•
Hardness
Color
Streak Test
Luster
Crystal Form
Cleavage / Fracture
Mineral Properties
Hardness - A measure of the resistance
of a mineral to abrasion or scratching.
Mohs Hardness Scale
Relative Scale
Hardest
Softest
10
9
8
7
6
5
4
3
2
1
Mineral
Diamond
Other Objects
Corundum
Topaz
Quartz
K-Feldspar 5.5 Glass,
Pocketknife
Apatite
Fluorite
3.5 Copper Penny
Calcite
2.5 Fingernail
Gypsum
Talc
Mineral Properties
Color
Colorless quartz
Purple quartz (amethyst)
Brueno Jasper
Mineral Properties
Streak – The color of a mineral in its
powdered form.
The Mineral Hematite Always Has a Red Brown
Streak Whether It Is the Metallic or Earthy Variety.
Mineral Properties
Luster – the
appearance or
quality of light
reflected from the
surface of the
mineral.
• Metallic vs. nonmetallic
• Nonmetallic – vitreous
(glassy), pearly, silky,
resinous, and earthy
Amethyst with vitreous luster
Mineral Properties
Crystal form – the
external expression of a
mineral’s internal orderly
arrangement of atoms.
Pyrite – Cubic
Crystals
Quartz -Hexagonal
Crystals
Mineral Properties
Halite
Calcite
Cleavage – The
tendency of a mineral
to cleave, or break,
along planes of weak
bonding.
Fluorite
Multiple cleavages in
fluorite, halite and calcite
Simple cleavage in micas
1 plane - Micas
3 planes – Halite (salt)
2 planes – K Feldspar
3 planes (rhombo.) - Calcite
Mineral Properties
Conchoidal fracture in quartz
FractureMinerals that
do not break
along
cleavage
planes are
said to
possess
fracture
Mineral Properties
Specific gravity –
compares the
weight of a
mineral to the
weight of an equal
volume of water.
High specific gravity of galena.
Additional Properties
• Effervescence - Calcite and powdered dolomite will
effervesce (fizz) in dilute hydrochloric acid (HCl)
• Smell- Sphalerite will give off a rotten-egg smell when
streaked on a streak plate. (Note: pure sulfur does not
smell like rotten eggs!)
• Magnetism- Magnetite (AKA Lodestone) will pick up
paper clips (weak samples will only be able to pick up
staples)
• Taste- Halite is rock salt and will taste salty. *Do not
taste the samples since some have been tested with
acid to see if it is calcite.
• Fluorescence- some minerals (mostly forms of calcite)
will glow in fluorescent colors under a black (UV) light.
• Double refraction- some clear forms of calcite (Iceland
Spar) will make a double image of words.
Additional Properties
Fluorescence
Double refraction
Uses of Minerals
• Gems: highly prized
minerals because they
are rare and beautiful
– Most gems are brighter and
more colorful than common
samples of minerals
– Ex: Emeralds, rubies,
diamonds
– Ex. Amethyst: a form of
quartz with traces of iron,
sapphires
– Trace amounts of elements
can make some gems
more rare than others =
More money
Uses of Minerals
•
Ores: a mineral is an
ore if it contains a
useful substance
that can be mined
for a profit
– Ex. Al from bauxite
– Fe from hematite
– Titanium from rutile
Asbestos
• A mineral with threadlike,
flexible fibers
– Used for insulation and fire
protection = doesn’t burn or
conduct heat
– When these fibers become
loose and airborne → often
get into the lungs where
they’ve been known to
cause cancer (carcinogen)