Mineral
Detective
Lab
#36
Purpose of Lab
• To learn how to use mineral identification
techniques to identify unknown minerals.
• To become more familiar with some
common minerals.
• To review the parts of a laboratory
experiment and report.
Lab Timeline
• MONDAY: Introduction of Formal Lab, break into
pairs, write Title, Introduction, Hypothesis,
Materials, Procedures, “Observations” column
• TUESDAY: In pairs, complete “Light
Interaction”, “Smell,” and “Streak,”
• WEDNESDAY: Mohls Hardness Scale, Set up
Solubility Tests
• THURSDAY: “Cleavage,” “Ice,” Finish
observations for “Solubility”
• FRIDAY: Use information to identify minerals,
write conclusion paragraph.
MONDAY
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On a blank sheet of paper…
• Your paper will have the following sections:
–
–
–
–
–
–
Title
Introduction Paragraph
Materials
Procedures ( just write “See Lab Instructions”)
Results (This will be the completed data table)
Modified Conclusion
Title and Introduction
• Name, date, period, #36 in the upper right hand
corner.
• Write “Mineral Detective Lab” across the top.
• On the first line, write “Partner(s): ________”
• Skip a line and write “INTRODUCTION”
• Please take 5 minutes to write ONE paragraph
that answers these questions…
– What is the purpose of this lab?
– Why is the information learned in this lab important?
– Who could benefit from this information?
Materials
• Skip a line and write
“MATERIALS.”
• Remember that to earn full
credit, EACH material must
have both an amount and
a size (if applicable.)
• Create a bulleted list that
includes the following:
– 1 small Magnifying
glass
– 8 different small mineral
specimens
– 1 Penny
– 1 small Streak plate
– 1 small Steel nail
– 1 Data table
– 9 medium sized ice
cubes
– 1 paper towel
– 16 100mL beakers (for
whole class)
– 400mL vinegar (for
whole class)
– 400mL tap water (for
whole class)
– 1 metal tray to hold
beakers
Procedures
• Skip a line and write “PROCEDURES.”
• Write “See Lab Instructions.”
Test #1: Observations
• Obtain 8 different mineral samples. They will
initially be identified using numbers 1-8.
• Match the mineral to its number using the
very brief descriptions in the “Procedures.”
• Use a magnifying glass to carefully observe
each mineral. Record a detailed description
in your data table.
• Please focus on TEXTURE and LUSTER.
Test #2: Light Interaction Test
• First, identify if each mineral is opaque,
translucent, or transparent. Record your
observations on the data table.
• Second, test all of your TRANSPARENT
minerals for double refraction.
– Do they cause any of the lines/letters to
appear double when placed on them and
slowly rotated? Record your observations on
the data table.
TUESDAY
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Test #6: Smell Test
• Some minerals have very unique or distinctive
smells. It is easiest to smell a mineral if you have
a fresh sample of its powder.
• Test the minerals in the following order:
8,7,6,5,4,3,2,1.
• Rub each mineral back and forth a few times on
the streak plate. Immediately smell the powder.
• Record all observations in the data table.
Test #3: Streak Test
• “Streak” is the color of the minerals
powder.
• Rub each mineral ONE OR TWO TIMES
ONLY on the streak plate.
• Record the color of the powder that rubs
off each mineral on the data table.
WEDNESDAY
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Test #4: Hardness
• Hardness describes how resistant a
mineral is to being scratched.
• A geologist named Freidrich Mohs
developed a scale for rating the hardness
of minerals: the higher the number, the
harder the mineral.
Test #4: Hardness
• .
Test #4: Hardness
• Can it be scratched with a nail?
NO
YES
(These
minerals
are >5)
(These minerals are <5 )
Can it be scratched with a
copper penny?
YES
These are <2
NO
YES
(These are <3)
These are
between 2-3
NO
Can it be scratched with a
fingernail?
(3-5)
Test #5: Cleavage
• Cleavage is a word used to describe how a mineral splits or
breaks.
• Observe the minerals to determine if they have…
– PERFECT CLEAVAGE: The broken surface is perfectly flat.
Light reflects off when tilted back and forth.
– GOOD CLEAVAGE: Some of the broken surfaces appear
perfectly flat. When the mineral is tilted back and forth in the
light, there appears to be ONE position that reflects light
very well.
– POOR/NO CLEAVAGE: The broken surfaces are irregular.
Although the mineral might be shiny, none of the surfaces
are perfectly flat.
THURSDAY
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Test #3: Double Refraction
• Lay each TRANSPARENT mineral across
the straight and wavy lines on the
instructions.
• Slowly rotate the mineral and see if any of
the lines appear “double.”
• If yes: this mineral has “double refraction”
and record this in your data table in the
“Light Interaction” column.
Test #7 ice
• Work with another group to conserve
resources!
• Place 8 ice cubes on top of a paper towel.
• Place each mineral on top of an ice cube.
• Make observations for at least 10 minutes.
• When finished, dry each mineral and put
back into tray.
Test #: Solubility
• This test will take 24 hours.
• This test will be completed as a class to
conserve resources.
• We will place each mineral in water and in
vinegar (weak acid) to see if they dissolve.
• We will record our observations tomorrow.
Time to Identify!
1.
2.
3.
4.
5.
6.
7.
Mineral has good or perfect cleavage………Go to 2
Mineral has poor/no cleavage……………….Go to 5
Mineral is opaque…………………………Feldspar
Mineral is translucent or transparent………..Go to 3
Mineral has double refraction…………………Calcite
Mineral does NOT have double refraction……Go to 4
Mineral is soluble in water and acid……………Halite
Mineral is NOT soluble in water and acid………Mica
Mineral is harder than 5 on Hardness scale……Go to 6
Mineral is softer than 5 on Hardness scale……Go to 7
Has greenish/black streak………………………Pyrite
Has no (colorless) streak…………………Rose Quartz
Has rotten egg smell……………………………..Sulfur
Has no smell……………………………….Hematite
Conclusion Paragraph
Please answer the following questions in your conclusion paragraph:
1.) What were the purpose(s) of this lab?
2.) Give the name of each mineral, describe it, (3-4
words) and explain what feature(s) “give away” its
identity.
3.) Identify 3 sources of error in this lab, and how
you could avoid these errors in the future.
4.) Discuss two questions that you still have about
minerals.
The end!
#36