Grade Level/Subject
High School Earth Space
Unit
Energy Flow - Rock Cycle
Enduring
Understanding
The processes of Earth are cyclical in nature,
continually reshaping the Earth and its
material with no loss or gain of matter.
ES 1c - Graph construction and interpretation
ES 2 – Scientific reasoning and logic
ES 4 – Minerals
ES 5a – Igneous Rocks
The Effects of the Rate of Cooling on Mineral
Crystallization
SOL Objectives
Title
Lesson Objective
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Inquiry Level
Materials Required
To observe crystal growth and
distinguish a single crystal
To note the development of crystal
structures in minerals under different
temperature conditions
To draw connections to the
development of different igneous rocks
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Light microscope
3 watch glasses
Small sample of Thymol
Bunsen burner
Ring stand
Wire gauze
Lighter
Gloves
Goggles
Forceps
Heat lamp
Ice
The Effects of the Rate of Cooling on Mineral Crystallization
Purpose:
To observe crystal growth and distinguish a single crystal
To note the development of crystal structures in minerals under different
temperature conditions
To draw connections to the development of different igneous rocks
Materials:
 Light microscope
 3 watch glasses
 Small sample of Thymol
 Bunsen burner
 Ring stand
 Wire gauze
 Lighter
 Gloves
 Goggles
 Forceps
 Heat lamp
 Ice
Warning: Avoid inhaling or skin contact with Thymol. If inhaled, remove to fresh air.
If contact with skin, flush with water and mild soap.
Background Information:
Most minerals that originate from a melt crystallize at room temperatures well
above the boiling point of water, so directly observing their crystal growth is difficult.
Thymol, an organic chemical, crystallizes near room temperature. Although it differs
from magma, certain principles of crystallization demonstrated in a thymol melt
pertain generally to crystallization of magma. Thymol is not poisonous but should be
handled with forceps, for it can irritate the skin and eyes.
Procedures:
You are responsible for creating an experiment that will test the rate of cooling on the
size of mineral crystallization using the materials above. Let the cooling sample at room
temperature be your control.
Identify:
Independent Variable
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Dependent Variable
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Control
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How will you record your independent variable?
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How will you measure your dependent variable?
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Write your hypothesis for this lab. How do you think temperature will influence the
size of the crystals? Why?
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Write up your steps for conducting this experiment. Have your steps approved by your
teacher before you gather your supplies and begin the lab.
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Use the blank data table below as a tool to record your findings. Use your data table to
construct a graph that will display your results.
Analysis:
1. Note your observations from your cooled samples below.
2. Discuss any factors that may have inadvertently influenced your results.
3. What effect does the rate of cooling have on crystal size?
4. What type of igneous rock would be representative of your sample that cooled
quickly? What about your sample that cooled slowly?
5. Why do you think cooling crystals at different temperatures plays a role in the
size of the crystals?
Conclusions:
Summarize this experiment and your results in 5-7 sentences.