Move It or Use It! Classifying Minerals Part 2 1
Team #4, Week 4, Day 2, Lesson 4
Subject Area
Earth Science: Classifying minerals. Part 2
Person Who Created This Lesson
Joan Aitken
Roles of Support Teachers
 Clarify information if students seem confused.
 Work independently with students who need additional help, either in small
groups or individually.
 Work with students who finish early by helping them find independent work on
the computers or leave the room for a learning activity, for example.
 Interject new perspective or provide procedural support if there is a learning or
behavior problem.
 Provide encouragement to students and lead teacher.
Length of Lesson
Approximately one hour.
Materials
Pencils or pens
Notebook paper
Epsom Salts
Baking Soda
Jars, plates, string (see experiment from 100 Science Experiments
Book: Peterson Field Guide to Rocks and Minerals, by F. H. Pough
Instructional Objective for the Group (Condition, Behavior, Criteria, Timeframe)
After the lecture, discussion, and experiment, the student will be able to classify at least
one real minerals based on its characteristics.—orally, through drawing, by posting to a
blog, or in writing-- with 80% accuracy, in one trial.
Advance Organizer (Script)
Today we’re going to continue discussing minerals and how to classify minerals based on
their characteristics.
The rationale is you will learn more effective and objective observation methods, which
you can use in an array of contexts.
To give you an overview to our plan, we will define a scientific experiment, conduct an
experiment, then classify some real minerals based on their characteristics.
Instructional Procedures (Method)
1. Handout on classifying rocks and minerals.
2. Video on Meterologist
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3. Earlier when we talked about rocks and minerals, some of you said we did an
experiment, which we did not. What is an experiment?
Discuss role of hypothesis. The independent variable is the variable you purposely
manipulate (change). The dependent variable is the variable that is being observed,
which changes in response to the independent variable. The variables that are not
changed are called controlled variables. Discuss observation.
4. Toothpaste squirt
5. Hall Wall Questions
6. Blog if time.
Guided Practice
All teachers will be involved in helping and correcting students individually or in small
groups, while they discuss experiments and conduct the experiment, and classify
minerals.
Independent Practice
After the lecture, discussion, and experiment, the student will be able to classify at least
one real minerals based on its characteristics.—orally, through drawing, by posting to a
blog, or in writing-- with 80% accuracy, in one trial.
Evaluation/Assessment
I will answer the question “Have I met the instructional objective?” by having students
demonstrate the instructional objective.
Review (Interactive Recap)
What we did: Today we discussed experiments, conducted an experiment, and classified
minerals according to their characteristics.
Connection to real world: You can increase your powers of observation and data
collection.
Reference (Source of Lesson)
Peterson Field Guide to Rocks and Minerals, by F. H. Pough
Andres, G., & Knighton, K. (2004). 100 science experiments. London: Usborne.
Experiment: The experiment instructions are on the following pages.
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Check Your Knowledge:
1. Minerals are not rocks.
2. Quartz is a common
3. Some minerals form through evaporation.
4. Color is the best way to identify a mineral.
5. Mineral crystals are always small.
6. A mineral crystal grows randomly.
True or False?
mineral.
Source: http://www.sdnhm.org/kids/minerals/games/true-false/games-tf1ans.html and
http://www.sdnhm.org/kids/minerals/
Color
Usually, we notice the color of a mineral first. Some minerals are easily identified by
color because they are never any other color. For example, malachite is always green.
Keep in mind, however, that color by itself isn't enough to identify a mineral. Chemical
impurities can change the color of a mineral without changing its basic make-up. For
example, quartz in its purest form is colorless and clear as glass. Quartz with traces of
iron becomes violet (amethyst). With traces of manganese, it turns pink (rose quartz). If
quartz is exposed to radiation, it turns brown (smoky quartz).
Streak
When a mineral is rubbed firmly across an unglazed tile of white porcelain (a streak
plate), it leaves a line of powder. This is called the streak. The color of the streak is
always the same, whether or not the mineral has impurities. For example, quartz leaves a
white streak, whether it's violet (amethyst), pink (rose quartz), or brown (smoky quartz).
The geode pictured here is lined with amethyst crystals.
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Transparency
Transparency describes how well light passes through a mineral sample.
There are three degrees of transparency: transparent, translucent, and
opaque. You can see objects through a transparent mineral. You can see
light, but no objects through a translucent mineral. You can't see anything
through an opaque mineral.
The sample of beryl shown here is nearly transparent.
Luster
Luster is the way the surface of a mineral reflects light. Luster should be observed on a
cut or freshly broken, untarnished surface. There are two general types of luster -metallic and non-metallic. The terms used to describe luster are:
* Metallic -- example: gold
* Vitreous (glassy) -- example: quartz, tourmaline
* Adamantine (brilliant) -- example: diamond
* Resinous (like resin or sap from a tree) -- example: sphalerite
* Greasy or waxy -- example: turquoise
* Pearly -- example: talc
* Silky -- example: asbestos
* Dull or earthy -- example: bauxite
Move It or Use It! Classifying Minerals Part 2 5
Hardness
The hardness scale was established by the German mineralogist, Friedrich Mohs. The
Mohs’ hardness scale places ten common or well-known minerals on a scale from one to
ten. One is the softest mineral and ten is the hardest. These are the minerals used in the
Mohs’ hardness scale:
Mohs' Hardness Scale
1
2
3
4
5
6
7
8
9
10
Talc Gypsum Calcite Fluorite Apatite Feldspar Quartz Topaz Corundum Diamond
To use the hardness scale, try to scratch the surface of an unknown sample with a mineral
or substance from the hardness scale (these are known samples). If the unknown sample
cannot be scratched by feldspar (6) but it can be scratched by quartz (7), then it's hardness
is between 6 and 7. An example of a mineral that has a hardness between 6 and 7 is pyrite
(6 to 6.5).
If you don't have minerals from the hardness scale on hand, here are some common
objects and their hardness values:
Common Objects and Their Hardness Values
2.5
3.5
5.5
6.5
8.5
Fingernail Penny Glass Steel knife Emery cloth
If an unknown sample can not be scratched by your fingernail (2.5) but it can be
scratched by a penny (3.5), then it's hardness is between 2.5 and 3.5. An example of a
mineral that has a hardness between 2.5 and 3.5 is calcite (3).
Cleavage
When a mineral sample is broken with a hammer, it breaks along planes of weakness that
are part of its crystalline structure. These breaks are cleavages. Some minerals break only
in one direction. Others break in two or more directions.
Some common forms of cleavage are cubic, rhombohedral, and basal. Cubic cleavages
form cubes (example, halite). Rhombohedral cleavages form six-sided prisms (example,
calcite). Basal cleavages occur along a single plane parallel to the base of the mineral
(example, topaz).
If a mineral breaks easily and cleanly in one or more directions, its cleavage is considered
perfect. For example, calcite cleaves perfectly along three planes. As the quality of the
break decreases, cleavage may be described as good, distinct, and poor or none. Some
minerals cleave perfectly in one direction and poorly in others. For example, gypsum
cleaves perfectly on one plane and poorly along two others.
Move It or Use It! Classifying Minerals Part 2 6
Fracture
Not all minerals cleave easily. Some fracture instead. Unlike cleavages, which
are usually clean, flat breaks, fractures can be smoothly curved, irregular,
jagged or splintery.
The most common types of fracture are conchoidal (quartz) , fibrous or splintery, hackly
(copper), uneven or irregular.
The sample of malachite shown here has a conchoidal fracture; it's smooth and curved.
Specific Gravity
Specific gravity is the density of a mineral. Special equipment is usually needed to find
out a mineral’s exact specific gravity. With a little practice, you can guess a mineral’s
specific gravity by hand. Some mineral samples will feel heavier than others, even if all
your samples are the same size. The heavier ones have a greater specific gravity. Here are
some examples of common minerals and their specific gravity ranges:
Minerals
Density
Specific gravity
sulfur, graphite
light
1-2
gypsum, quartz
medium
2-3
fluorite, beryl
medium heavy
3-4
corundum, most metal oxides heavy
4-6
native gold, platinum
19
heaviest
Crystal Form
Minerals grow in specific shapes, and usually crystallize into one of six crystal systems.
The axes of the crystal, the angles at which the axes intersect, and the degree of
symmetry define each system.
 Isometric -- Also called the cubic crystal system. Crystals are usually shaped like
blocks, with similar and symmetrical faces. The crystal has three axes of
symmetry, all at right angles to each other, and all of the same length.
Example: pyrite.
 Tetragonal -- Typically, the crystals are shaped like four-sided prisms and
pyramids. Each crystal has three axes, all perpendicular to one another. Two axes
are the same length and lie on a horizontal plane. The third axis is not the same
length and is at a right angle to the other two.
Example: zircon.
Move It or Use It! Classifying Minerals Part 2 7
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Hexagonal -- These crystals are usually shaped like six-sided prisms or pyramids.
Each crystal has four axes of symmetry. Three lie in the same plane, are the same
length, and intersect at 120° angles. The fourth axis is not the same length, and is
perpendicular to other three.
Example: beryl.
Orthorhombic -- These crystals are short and stubby. Each crystal has three
unequal axes, all at right angles to one another.
Example: topaz
Monoclinic -- Crystals are short and stubby with tilted faces at each end. Each
crystal has three unequal axes. Two axes lie in the same plane at right angles to
each other. The third axis is inclined.
Example: gypsum.
Triclinic -- Crystals are usually flat with sharp edges, but exhibit no right angles.
Each crystal has three unequal axes. None are perpendicular to one another.
Example: feldspar.
Answer Key
1. Minerals are not rocks.
THIS IS TRUE.
A mineral is a crystalline solid.
A rock is a consolidated material made of grains of one or more minerals.
2. Quartz is a common mineral.
THIS IS TRUE.
Quartz is one of the most common minerals on Earth. It occurs in all geological environments, and makes
up most of the dust in air.
3. Some minerals form through evaporation.
THIS IS TRUE.
When mineral-bearing water evaporates, mineral crystals are left behind. These are called evaporites. An
example of an evaporite is gypsum.
4. Color is the best way to identify a mineral.
THIS IS FALSE.
Color is one of the first things we notice about a mineral, but it isn't the best way to identify it. You need to
consider several properties as well as color when identifying a mineral.
5. Mineral crystals are always small.
THIS IS FALSE.
Crystals can become enormous if allowed to grow freely. Some specimens of beryl and spodumene
measure several meters and weigh many tons.
6. Mineral crystals form randomly.
THIS IS FALSE.
Mineral crystals form in definite, repeating patterns. Its external shape -- smooth, symmetrical flat surfaces
-- reflects its atomic structure.
Source: http://www.sdnhm.org/kids/minerals/games/true-false/games-tf1ans.html
Move It or Use It! Classifying Minerals Part 2 8
Wall in the Hall Questions (Rocks and Minerals)
1. What information do rocks and minerals give us?
2. How long ago did some rocks on the surface form?
3. Where do sandstone and limestone come from?
4. Where do red sand rocks come from?
5. What type of history do metamorphic rocks show?
6. Where did igneous rocks come from?
7. What are minerals?
8. Is a diamond a mineral?
Questions in the Hall Week 4 (Rocks and Minerals) Answers
1. Rocks and minerals give us information about the early history of earth.
2. The earth is 4.5 billion years old. The oldest chunk of earth’s crusts found dates
to 3.8 billion years ago. Some surface rocks formed a billion years ago.
3. Old freshwater lakes: sandstone and limestone.
4. Red sand rocks: an old shoreline.
5. Metamorphic rocks were mountains.
6. Igneous rocks, like granite were molten lava from below.
7. Mineral has a fully definite composition and shape (crystals). Regardless of
external form, always has an orderly internal form.
8. Yes.
Move It or Use It! Classifying Minerals Part 2 9
A Bright Smile from Toothpaste and Minerals http://www.mii.org/teacherhelpers.html
ROCKS IN YOUR MOUTH
by John Sznopek, USGS
Did you know that the stuff you brush your teeth with contains
rocks? The toothpaste we all use every day to brush our teeth
contains many different kinds of materials, including, amazingly,
crushed rocks. Nevertheless, that's only part of the story. Let's start
at the beginning and introduce you to this common household product. Later, we'll come
back to those useful rocks.
After we eat foods containing sugar, armies of bacteria living in our
mouths convert sugar to acid. This acid can attack our teeth and
cause cavities. Brushing our teeth with toothpaste helps to prevent
this through mechanical and chemical processes. The most obvious
process in brushing is a mechanical action which cleans the food debris and plaque from
our teeth. One of the chemical processes that takes place when you brush your teeth is the
neutralization of acid so that it can no longer attack. Yet another chemical process is the
removal of stains by a special whitening agent. Chemicals contained in toothpaste may
also kill bacteria. Killing bacteria lessens the formation of plaque. The plaque we are
talking about is not an award hanging on the wall. This type of plaque is a thin layer on
our teeth which contains pieces of food, saliva and bacteria. If plaque is not removed
from our teeth, tartar, also called calculus, eventually forms. Tartar is plaque that has
hardened on our teeth. Formation of tartar can then lead to cavities
or gum disease, neither of which we want. Toothpaste helps to
reduce tartar buildup, but only professional cleaning removes tartar.
When toothpaste was first developed, its only function was to clean
teeth. So, its composition was fairly simple. Your grandparents
probably remember brushing their teeth with table salt or baking
soda. That's really basic. Today, toothpaste does a lot more. It helps prevent tooth decay
and gum disease. It also desensitizes and whitens teeth. These modern dentifrices
(another name for toothpaste) remove stains and food particles from our teeth, and also
have certain desirable physical properties. For example, you would not want the
toothpaste to run off the brush and down your arm, so consistency is important.
Toothpaste has evolved into quite complex formulas. It has to fulfill many functions, both
therapeutic and cosmetic.
Toothpaste is composed of many different ingredients, each having a
very special function. Searching for active ingredients led to the use
of stannous fluoride. It could be combined safely with toothpaste
and prevented tooth decay. Fluoride has been added to drinking
Move It or Use It! Classifying Minerals Part 2 10
water for 50 years and has been available in toothpaste since the 1950s. One of the
principal natural sources of fluoride is fluorspar. Fluorspar is a mineral composed of
calcium and fluorine. Although fluorspar ore is found worldwide, it is not produced in the
United States. China is the world's largest producer of fluorspar ore. Other active
ingredients incorporated into toothpaste loosen plaque and prevent its buildup. Additional
chemical additives are incorporated in some toothpaste to promote healthy gums.
What keeps toothpaste together? What keeps it smooth, creamy, and prevents it from
drying out and becoming hard as a rock? The answer is a humectant. Humectants are a
major element in all toothpastes. They help to retain moisture and make toothpaste
creamy and squeezable. Glycerin and sorbitol are two common humectants. Glycerin,
also called glycerol, is a by-product of soap manufacturing. Sorbitol is found in some
berries and fruits. Both are alcohols that may be synthetically produced, mix with water,
are odorless, and sweet tasting. Most toothpastes contain glycerin which acts both as a
plasticizer and a moistening agent.
Now, let's use our imaginations to understand the purpose of some
other important materials in toothpaste. Picture an ocean, with its
sandy beach, foaming surf, and some seaweed which has washed up
on this beach. Each of these represents some components of the
toothpaste. When you clean your teeth, the action of rubbing
toothpaste against your teeth produces a foam similar to that produced at the beach.
Brushing activates a detergent called sodium lauryl sulfate. The
foam that is generated helps the toothpaste to penetrate and loosen
deposits on the surface of your teeth.
Chemicals made from seaweed are used as binders. Binders help the
toothpaste maintain its shape as it sits on your toothbrush. Various
types of gums, but not the chewing variety, are also used to keep all
the ingredients together in a nice blob. Some examples of these gums are xanthan gum
and cellulose gum.
Yet another example of 'rocks in your mouth' is sand (remember the
beach?), which is composed of quartz or silicon dioxide. As sand, it
is so hard that it would scratch your teeth. So the mineral is
processed into a more useable form, called amorphous silica, which
is much softer. Silica also acts as a thickener. This property keeps
the liquids and solids in the toothpaste from separating.
Other rocks or rock products are used in toothpaste. As much as half
the weight of toothpaste comes from polishing agents, also called
abrasives. These help scrub our teeth and remove plaque. It is a myth
that abrasives in toothpaste wear away our tooth enamel. The little
enamel erosion that does occur, however, is probably due to overzealous brushing. Several minerals are used for polishing teeth. One
Move It or Use It! Classifying Minerals Part 2 11
of these is alumina trihydrate, a principal component of many bauxite ores. Bauxite is
also the main ore mineral for aluminum. Alabama is a principal domestic source of
alumina trihydrate. Additional polishing agents are calcium carbonate and phosphate salts
such as dicalcium phosphate, calcium pyrophosphate, and insoluble sodium
metaphosphate. Although some of these minerals are mined in the United States, others
are imported from around the world.
One of the most common polishing agents used today is sodium
bicarbonate, the chemical name for baking soda. Important deposits
of this mineral are located in California and Wyoming. Baking soda
is incorporated in as much as one third of all toothpaste today. Its
popularity is due to its safety, its low cost, and its compatibility with
fluoride. Compatibility with fluoride is very important because other
polishing agents can block the fluoride's effectiveness in preventing tooth decay. The
carbonates also neutralize acids that are produced in our mouths, thus helping to prevent
cavities. In the United States, we use almost a pound of toothpaste per person per year.
Altogether then, we use more than 37,000 pickup truck loads of abrasive minerals in our
mouths every year.
These specific minerals have two drawbacks, they don't have a great
taste and they don't provide a splash of color, so flavoring,
sweeteners, and colorants are added to toothpaste. A wide variety of
flavoring oils are used to give products a distinctive and pleasant
taste. In most toothpastes, saccharin or cyclamate are added for
sweetening. The clean white color of toothpaste is typically due to
yet another mineral, rutile or titanium dioxide. It is mined in the United States, especially
Florida, and overseas and is used as a pigment in endless
applications.
Toothpaste tubes are made from three basic materials: aluminum,
plastic, and glue. Typically, toothpaste tubes have outer and inner
layers of polyethylene, a plastic, with a layer of aluminum foil glued
between them. The inner plastic layer does not react chemically with
the active ingredients in toothpaste. The layered tube is the choice of
most toothpaste producers. This is because the foil provides the feel people prefer and
allows the tube to be rolled and crimped. As mentioned earlier, aluminum is obtained
from bauxite ore. Aluminum metal for foil is produced from imported ore. Plastics are
derived from oil and natural gas, which are found throughout the
world.
According to the Tube Council of North America, more than 800
million tubes have been manufactured for toothpaste in North
America in each of the last several years. Considering the average
toothpaste tube to be approximately six inches long, if they were laid
end-to-end, one year's production would circle the earth more than
three times.
Move It or Use It! Classifying Minerals Part 2 12
Not very long ago, toothpaste was very simple and composed of
only a few major components like table salt or baking soda. Today,
formulas have become far more complex due to the incorporation of
ingredients that produce therapeutic and cosmetic benefits. Even
with the addition of these important additives, toothpaste must
maintain its great taste and clean our teeth, as we have come
accustomed to over the years. So the next time you brush your teeth, consider the
complexity of this common product, and don't forget the important contributions that
these 'rocks in your mouth' provide us every day.
AN INFORMATIVE TEST
[Circle the correct answer]
1. Tartar is the same as calculus.
True
False
2. Today, toothpaste is a simple product with a few components.
True
False
3. Fluoride has been included in toothpaste the last ten years.
True
False
4. You can remove tartar by brushing regularly.
True
False
5. Chewing gum is used in toothpaste.
True
False
6. Baking soda is an expensive additive.
True
False
7. Titanium dioxide is used in toothpaste as a whitener.
True
False
8. We use approximately one pound of toothpaste per person per year.
True
False
Move It or Use It! Classifying Minerals Part 2 13
Experiment to Engage: How To Make a Mentos & Diet Soda Chemical Volcano
Eruption
Instructional Connection:
1. Think about this experiment and how it relates to today’s lessons. We will do the
experiment later in the day.
2. How does this experiment relate to earth science?
3. What can we use from the scientific method to make this experiment scientific?
“The scientific method attempts to explain the natural occurrences (phenomena)
of the universe by using a logical, consistent, systematic method of investigation,
information (data) collection, data analysis (hypothesis), testing (experiment),
and refinement to arrive at a well-tested, well-documented, explanation that is
well-supported by evidence, called a theory.”
From Anne Marie Helmenstine, Ph.D.,
Your Guide to Chemistry.
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Chemical volcanos are classic projects for science fairs and chemistry demonstrations.
The mentos and diet soda volcano is similar to the baking soda volcano, except the
eruption is really powerful, capable of producing jets of soda several feet high. It's messy,
so you might want to do this project outdoors or in a bathroom. It's also non-toxic, so kids
can do this project.
Difficulty: Easy
Time Required: chemical volcano takes a few minutes to set up and erupts for a few
seconds
Here's How:
1. First, gather your supplies. You can substitute another candy for the Mentos, such
as M&Ms or Skittles, but ideally you want candies that stack into a neat column
with minimal space between them, have a chalky consistency, and barely fit
through the mouth of a 2-liter bottle.
2. Similarly, you could substitute normal soda for diet soda. The project will work
just as well, but the resulting eruption will be sticky. Whatever you use, the
beverage has to be carbonated!
3. First, you need to stack the candies. The easiest way to do this is to stack them in
a test tube narrow enough to form a single column. Otherwise, you can roll a
sheet of paper into a tube just barely wide enough for a stack of candies.
4. Place an index card over the opening of the test tube or end of the paper tube to
hold the candies in the container. Invert the test tube.
5. Open your full 2-liter bottle of diet soda. The eruption happens very quickly, so
set things up: you want the open bottle - index card - roll of candies so that as
soon as you remove the index card, the candies will drop smoothly into the bottle.
6. When you're ready, do it! You can repeat the eruption with the same bottle and
another stack of candies. Have fun!
What You Need:
 roll of mentos candies
 2-liter bottle of diet soda
Move It or Use It! Classifying Minerals Part 2 14
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index card
test tube or sheet of paper
a mop for cleanup
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