Transcript Minerals are NEAT!

Overview
3rd and 4th nine weeks
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Geology (study of Earth)
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Minerals
Rocks
Plate Tectonics
Earthquakes
Volcanoes
Earth’s History and Fossils (evolution)
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Minerals
Chapter 3 (orange book)
Chapter 4 (green book)
Definition
A 1 naturally-occurring, 2 inorganic 3 solid
with a 4 definite chemical composition.
Study of: Mineralogy
Branch of: Geology (study of the Earth)
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Definition/Rules (please consult notes)
1.
If we melted sulfur, would it be a
mineral?
If Calcite had a chemical composition
of CaCO2, would it be a mineral?
If we made a diamond with PERFECT
cleavage, would it be a mineral?
If a fossil had a hardness of 11, would
it still be considered a mineral?
2.
3.
4.
How many known minerals are there?
2000?
3000?
4000?
6000?
4,900 known mineral species – according to wikipedia.com
4,349 Total Valid Species - International Mineralogy
Association
6,293. The official list of mineral names, updated in 2009,
comprises 6,293 minerals. This list, published by the Commission
on New Minerals Nomenclature and Classification (CNMNC),
includes not only approved minerals, but also hypothetical,
questionable, discredited and unofficial minerals. The number of
known minerals grows every year ‘“ according to a CNMNC
annual report, about 60 new-mineral proposals are analysed each
year.
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Over 3000 identified minerals (according to textbook)
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Made of elements, which can be found on the periodic
table - pg. 61.
Example:
1. Silicates are made of silicon
and oxygen, chemical formula of SiO2
2. Halite made of sodium and
Chlorine, chemical formula NaCl
3. Pure elements – sulfur, copper, gold,
silver, etc.
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Minerals make up rocks
 Example: Granite is made of quartz, mica and feldspar
Let’s Review what we know…
How many minerals exist on Earth?
 How many “common” minerals are found
on Earth?
 What four characteristics do all minerals
share?
 What are minerals made of?
 What do minerals combine to form?
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Let’s look at the three groups of minerals…
Groups of Minerals – open to page 88
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Silicates:
1.
2.
3.
minerals made ofSilicon & Oxygen(SiO2)
Quartz - SiO2
Feldspar - KAlSi3O8
Anthophyllite - (Mg,Fe)7Si8O22(OH)2
Carbonates:
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Carbonate minerals are those
minerals containing the carbonate ion: CO3
1. Calcite
2. Dolomite
Evaporites:
Minerals that are formed from ions in
solution being left behind as water evaporated
1. Halite
2. Gypsum
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What two elements are most
common in the Earth’s crust?
Therefore, what mineral family do
you think is most abundant?
What two minerals do you think are
two of the most common in the
Earth’s crust?
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Tables at bottom of page 88
Advanced Lab Report –
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Written Lab Report
Introduction & Conclusion
For each station:
 Define the physical, chemical or special property from that
station
 Describe procedure you used and lab equipment at that
station
 Describe very specific results – data table if necessary
 Address questions from Standard Lab Report
(use it as a skeleton for your report)
Mineral ID Lab –
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Purpose: We will be identifying minerals by
testing minerals’ physical properties
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We will also be using:
 Observations
 Chemical Properties
 Special Properties
Subjective – opinion, sometimes difficult to
classify.
 Objective – numeric – can not be argued
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Physical Properties
1. Color - unreliable in identifying minerals
*Observation/Appearance is often times NOT
enough to identify a mineral – we need to test
other physical properties.
(1.) Color
– reliable?
Calcite
See why testing other physical/chemical
properties is necessary!
Pyrite
Nearly 300 color variations of diamonds!
Reliable colors
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In a select few
minerals, such as
sulfur and olivine,
color IS a reliable
indicator.
(2.)Luster-
the way a mineral
reflects light
Two main types of luster:
1. Metallic – looks shiny
2. Nonmetallic
Dull, Earthy, Pearly,
Vitreous, Gumdrop,
Glassy, Silky, Resinous,
Greasy/Oily
(3.)
Streak
The color of a mineral in powder form
 We use an unglazed porcelain plate to test
for streak
 What if the mineral shows no streak?
 More reliable or less reliable than color?
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Be able to name minerals that display the
same, and different color/streak
combinations.
(4.) Hardness
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How easily a mineral can be scratched
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Whose hardness scale did we use?
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Moh’s Scale of hardness – pg. 91
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Hardest and softest?
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We will use:
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Fingernail - 2.5
Glass - 5.5
Streak plate – 6.5
(5.)
Cleavage and Fracture
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Determined by internal, atomic arrangement
Cleavage - to break along a flat surface
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Fracture - to break along a jagged surface
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Can a mineral have both?
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Cleavage
Fracture
Conchoidal fracture is a curved breakage
(6.) Acid
test – identifying Carbonates
Calcite (CaCO3) reacts with hydrochloric Acid HCl
(lower case L, not an i)
 CaCO3 + HCl ---> CO2 + H2O
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Actual: CaCO3(s) + 2 HCl(l) → CaCl2(l) + CO2(g) + H2O(l)
Reaction shown by “effervescence”
 Example of a chemical property
 Safety procedures necessary at this station
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Effervescence
(7.)
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Specific Gravity
Specific gravity is the ratio of the density of a
substance to the density of water
Density = mass/volume
 Density of a solid: grams/cm3
 Density of a liquid: grams/mL
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1 cm3 = 1 mL
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Specific Gravity of 19.28 means it is 19.28 times
more dense than the same volume of water.
Special Properties – pg. 94
Taste – Halite
 Odor – sulfur
 Magnetism – magnetite
 Double refraction – Icelandic Spar Calcite
 Fluorescence
 Effervescence –carbonates (calcite &
dolomite)
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Double Refraction
Fluorescence
Crystal Size
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In minerals formed from magma, crystal size
indicates the speed the magma/lava cooled
(solidified).
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Large crystals – slowly
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Small crystals – quickly
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No crystals – very quickly
Lab Safety
Hydrochloric Acid
 Use one drop of HCl
 Goggles are mandatory
 Clean minerals after use
 Keep station clean/dry
 Hardness station - glass plate remains on lab
table
 No licking minerals at any other station than
“taste”. Wash minerals when you’re done.
 Pick up and replace ONE mineral at a time
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Know these minerals!!!
Diamond - hardest mineral
 Talc - 1 on Moh’s scale
 Sulfur - example of odor & reliable color
 Calcite - reacts with HCl
 Halite - (NaCl) taste
 Pyrite - (fool’s gold) color/streak
 Magnetite - displays magnetic characteristics
 Icelandic Spar Calcite – Double Refraction
 Your birthstone
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How do we get and use
Minerals?
Mine the ore
A mineral is an ore if it can be
mined at a profit
 Processed and sometimes
smelted
 Refine and purify the ore
 Gems often need cut/polished
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Smelting
To melt (ore) in order to separate the metal
contained
 The ore and the valuable mineral must have
different melting temperatures
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Smelting
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Do not confuse smelting with smelting
(catching small fish called smelt)
Gems or gemstones
Rare and beautiful minerals
 Special varieties of another mineral
 Examples of gems and their common mineral
forms are:
 Topaz --> Topaz
 Ruby --> Spinel
 Emerald --> Beryl
 Sapphire --> Quartz
 Amethyst--> Quartz
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Precious Minerals: diamond,
ruby, sapphire and emerald,
(pearl) (amethyst)
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Semiprecious Minerals – garnet, tanzanite,
fine tourmaline, spinel, and aquamarine,
Uses of minerals and gems
Diamonds - cutting, saw blades, drill bits
 Quartz – electronics, time pieces, computers,
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semiprecious gemstone
Gems - jewelry, valuable
 Some ore minerals often contain valuable elements
 From these minerals we get aluminum, titanium,
zinc, etc.
 Graphite - pencils, lubricant
 Gypsum - wallboard, cement
 Sulfur – fireworks, weapons
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Other Uses for Minerals
Corundum – used for abrasives
 Bauxite – aluminum ore
 Halite – food seasoning and
preservation
 Talc – paper, ceramics
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True or False
A diamond will leave a WHITE streak on a
streak plate.
 A gem is plentiful and ugly!
 The streak plate we used in class is a glazed
porcelain plate
 Since gypsum has large crystals, it probably
formed by cooling slowly.
 A mineral is always organic.
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Review:
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The formula for the calcite reaction
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Native minerals– what are these?