Download Teacher Guide - Price9thScience

Teacher Guide: Mineral Identification
Learning Objectives
Students will:
 Find the mass and volume of a mineral sample with a balance and a graduated cylinder.
 Calculate the density of a mineral sample by dividing its mass by its volume.
 Measure and observe the following mineral properties:
o Crystal form
o Luster
o Hardness
o Streak
o Reaction to acid
 Use a key to identify a mineral sample based on its properties.
Vocabulary
crystal, density, hardness, luster, mass, mineral, streak, volume
Lesson Overview
The Mineral Identification GizmoTM allows students to
observe, measure, and identify 26 mineral samples.
The Student Exploration sheet contains a warm-up
and two activities:

Warm-up – Students learn how to measure
mass and volume in order to calculate density.

Activity A – Students record data about a
single mineral sample and use a key to identify
the sample.

Activity B – Students apply their learning to
identify additional mineral samples.
Observing a mineral’s streak
Suggested Lesson Sequence
1. Pre-Gizmo activity: What is a mineral?
( 10 – 15 minutes)
Provide students with a variety of rock and mineral samples. Use rocks that are clearly
mixtures such as granite, schist, sandstone, conglomerate, etc. Try to include minerals
that look like crystals, such as quartz, mica, and halite (rock salt). Ask students to sort
the samples into a pile of rocks and a pile of minerals, and then come up with a definition
of each. (Rocks are basically mixtures of different minerals, while minerals are “pure.”)
2. Prior to using the Gizmo
( 10 – 15 minutes)
Before students are at the computers, pass out the Student Explorations and ask
students to complete the Prior Knowledge Questions. Discuss student answers as a
class, but do not provide correct answers at this point. Afterwards, if possible, use a
projector to introduce the Gizmo and demonstrate its basic operations.
3. Gizmo activities
( 15 – 30 minutes per activity)
Assign students to computers, and pass out a Mineral Key to each student. Students
can work individually or in small groups. Ask students to work through the activities in
the Student Exploration using the Gizmo and the Mineral Key. Alternatively, you can use
a projector and do the Exploration as a teacher-led activity. (Note: Calculators would be
very helpful for calculating density. If students do not have their own, they can use the
calculators on their computers.)
4. Discussion questions
( 15 – 30 minutes)
As students are working or just after they are done, discuss the following questions:

Which properties were most useful for identifying minerals? Why?

Which properties were least useful for identifying minerals? Why? (Color is an
example, as many minerals are found in a variety of colors.)

What are at least four ways you could distinguish gold from pyrite? (Gold is
denser and softer than pyrite. Pyrite has a dark streak and cubic crystals.)

What are three ways you could distinguish a diamond from a quartz crystal?
(Diamond is harder and denser than quartz. Quartz crystals are hexagonal.)
5. Follow-up activity: Identifying minerals
( 30 – 60 minutes)
All of the tests in the Gizmo can be done in the classroom with materials that are
relatively easy to obtain. You can do hardness tests with fingernails, pennies, glass
bottles and stainless steel. Balances and graduated cylinders are commonly available in
schools. Any unglazed porcelain can be used for a streak plate. Mineral samples can be
obtained from science supply companies or borrowed from other schools.
(Safety note: If you use hydrochloric acid, use a diluted solution. Wear goggles, aprons,
and rubber gloves. If acid makes contact with skin or eyes, flush with plenty of water.)
There are many other popular mineral activities. Grow crystals of halite, Epsom salts or
sugar. Model the atomic structure of minerals such as halite, diamond, or graphite using
toothpicks and gumdrops. See Selected Web Resources for more ideas.
Scientific Background
A mineral is defined as a solid material with the following characteristics:

Minerals are naturally occurring. Synthetic crystals such as cubic zirconia are not
considered minerals.

Minerals are inorganic, not formed by living things. Organic compounds, such as
sugars and proteins, are not considered minerals.

Minerals are crystalline. In a crystalline
substance, atoms are arranged in repeating
patterns. The shape of the crystal often
reflects the arrangement of atoms, as in
halite. (In the diagram, red dots represent
sodium atoms and blue dots represent
chlorine atoms.)
Halite crystal and atomic structure

Unlike rocks, minerals have a definite chemical composition. The chemical formula of
halite is NaCl, which indicates that halite is always made of sodium (Na) and chlorine
(Cl). The formula for biotite mica is much more complex: KMg 3AlSi3O10(OH)2!
Minerals form in many ways. As molten rock (magma or lava) cools and solidifies, crystals of
quartz, feldspar, mica and other minerals grow. Superheated water moves through cracks in
bedrock, dissolving and later precipitating crystals of quartz, mica, gold, silver, and other
minerals. Minerals such as halite and gypsum precipitate out of seawater as it evaporates.
Current Events Connection: Diamonds
“A Diamond is Forever” was a slogan that changed an entire
industry. Coined for the De Beers company in 1947, the
tagline helped to trigger a surge in the popularity of diamonds
that lasts to this day.
Diamonds have many iconic qualities. While diamonds are
generally white or clear in color, their ability to scatter light
(“fire”) is superior to any other mineral. Diamonds are pure
carbon, just like the soft graphite in a pencil. But while graphite
is quite soft, diamonds owe their incredible hardness to the
way that carbon atoms are arranged and bonded.
Uncut diamond
Diamonds form when carbon is compressed at enormous pressures, over 100 kilometers below
Earth’s surface. Diamonds are carried upwards by volcanic eruptions that originate deep in the
Earth. The resulting deposits, called kimberlite pipes, are named after the city of Kimberly,
South Africa.
In some diamond-rich but politically unstable countries, exports of so-called conflict diamonds
have been used to fund rebellions and civil wars. During the 1990s, diamonds were mined and
exchanged for arms by the RUF, a rebel group in Sierra Leone. Their brutal war was featured in
the recent movie Blood Diamond (NOT appropriate for children). Conflict diamonds have also
helped to fuel wars in Liberia, Angola, Congo and the Ivory Coast.
Selected Web Resources
Mineral identification: http://geology.csupomona.edu/alert/mineral/minerals.htm
Mineral properties: http://www.rockhounds.com/rockshop/mineral_id/
Rocks for kids: http://www.rocksforkids.com/RFK/TableofContents.html
Crystal growing activities:
Salt: http://library.thinkquest.org/J002289/crystals.html
Borax: http://chemistry.about.com/cs/howtos/ht/boraxsnowflake.htm
Epsom salts: http://www.exploratorium.edu/science_explorer/crystal.html
Sugar: http://www.exploratorium.edu/cooking/candy/recipe-rockcandy.html
Crystal structures:
Halite: http://stokes.byu.edu/nacl.htm
Diamond/graphite: http://www.avogadro.co.uk/structure/chemstruc/network/g-molecular.htm
Diamond formation, use, and history: http://en.wikipedia.org/wiki/Diamond