Download Minerals - Marblehead High School

M.A.S.T. Convention
Boxborough, MA - 2009
Mineral Formation - Background
Critical Thinking and Collaborative Learning
Session 76
Presented by Mark D. Greenman
Einstein Fellow, National Science Foundation
[email protected]
The Magma Chamber
Magma is a homogenized soup of minerals and/or mineral
components (this includes elements like Iron (Fe), Aluminum
(Al), gold (Au), lead (Pb), Magnesium (Mg), etc. and ions like
(SiO4), (SiO3), (AlSi3O8), (CO3), etc). The magma is so hot that
individual molecules of these minerals can not form fixed intermolecular bonds and cations like Al, Fe, Mg, etc. and anions
like (SiO4), (SiO3), (CO3), etc. can not maintain intact network
structures of bonded cations and ions
Point of Information: The mineral composition of a magma pocket varies.
The silicate content is usually between 50 and 70 percent. The more silicate
the more viscous is the magma.
Mark D. Greenman.
[email protected]
(781) 248-4952
The Magma Chamber
• As the magma cools these compounds, elements and ions
can begin to form fixed molecular bonds and network
structures (they begin to crystallize out of the magma soup).
• Each type of mineral begins this process at a different temperature.
• Each type of mineral ends this process at a different temperature.
• The crystallization process takes place within a specific range of
temperatures (too hot and fixed bonds can’t form - too cool and the
molecules that make up the mineral can no longer move to join other groups
of like molecules).
• The longer the magma stays within this range of temperature the larger the
“mineral clumping.”
Mark D. Greenman.
[email protected]
(781) 248-4952
Minerals
A Mineral is: (1) a pure substance† (i.e., has a definite
chemical composition with unique physical properties);
(2) is in the solid state; (3) is naturally occurring; (4) is
free of organic materials.
† The geologist definition of a “pure substance” and the chemist definition are
not quite the same. A feldspar sample with a small number of Aluminum
sites replaced by a chemically similar element in the anion would still be
classified as feldspar by a geologist even though the chemist would not agree
that the sample is pure. This allowance for “impurities” gives rise to the
variation in colors within a specific mineral and explains why a mineral can
have a range of temperatures to crystallize. A truly pure substance
crystallizes at a unique single temperature.
Mark D. Greenman.
[email protected]
(781) 248-4952
Minerals
A Mineral is: (1) a pure substance† (i.e., has a definite
chemical composition with unique physical properties);
(2) is in the solid state; (3) is naturally occurring; (4) is
free of organic materials.
Silicate Minerals: By weight, silicon constitutes 28% of the Earth’s crust
while Oxygen comprises 47% of the Earth’s crust.
Quartz
SiO2
Feldspars
… (AlSi3O8)
Hornblende
… (Si8O22)(OH)2
Mica
…(AlSi3O10)(OH)2
Rule of thumb: Silicate based minerals with cations of Iron (Fe), Magnesium (Mg), or
Calcium (Ca) tend to be dark. Those with Aluminum (Al) or Potassium (K) are light.
Mark D. Greenman.
[email protected]
(781) 248-4952
Minerals
A Mineral is: (1) a pure substance† (i.e., has a definite
chemical composition with unique physical properties);
(2) is in the solid state; (3) is naturally occurring; (4) is
free of organic materials.
Other Important Mineral Groups: Sulfide, sulfate, carbonate, and
oxide based minerals.
Galena
PbS2
Mark D. Greenman.
Gypsum
Ca(SO4)
Calcite
Ca(CO3)
[email protected]
Corundum
Al2O3
(781) 248-4952
Minerals
A Mineral is: (1) a pure substance† (i.e., has a definite
chemical composition with unique physical properties);
(2) is in the solid state; (3) is naturally occurring; (4) is
free of organic materials.
Other Important Mineral Groups: Elements such as gold, silver,
diamonds, and sulfur.
Quic k Ti me™ and a
dec ompres s or
are needed to s ee t his pic t ure.
Gold
Au
Mark D. Greenman.
Quic kT i me™ and a
dec om pres s or
are needed t o s ee thi s pi c ture.
QuickTi me™ and a
decompressor
are needed to see t his pict ure.
Silver
Ag
Diamonds
C
[email protected]
Sulfur
S
(781) 248-4952
Igneous Rocks - A Mixture of Minerals
Mark D. Greenman.
[email protected]
(781) 248-4952
M.A.S.T. Convention
Boxborough, MA - 2009
Mineral Formation - The Activity
Critical Thinking and Collaborative Learning
Session 76
Presented by Mark D. Greenman
Einstein Fellow, National Science Foundation
[email protected]
Organizing the Classroom
Mineral
Name
Quartz
Light Feldspar
Dark Feldspar
Olivine
Corundum
Hematite
Formation
Temperature
800-700C
1000-800C
1100-900C
1200-1100C
1000-800C
800-700C
Food
Composition
Fl3
Sw1(Bs1Fl1)
C2(Bs1Fl1)
Sb3Fl1
Bs1S2
Sb3S2
The Team: Choose a captain, a temperature monitor, and 2 scientists.
The captain and the 2 scientist pick two minerals to study.
The Supplies: The captain gets the mineral cards.
The temperature
monitor gets a stopwatch, 6 spoons, and 6 baggies. The 2 other scientists
get between them the 6 bowls filled with the ions.
The Lab Bench: Each scientist and the captain get 2 baggies, 2
mineral cards, and 1 spoon. The ion bowls are placed on the table so they
are in easy reach for all members of the team.
Mark D. Greenman.
[email protected]
(781) 248-4952
Organizing the Team
Mineral
Name
Quartz
Light Feldspar
Dark Feldspar
Olivine
Corundum
Hematite
Formation
Temperature
800-700C
1000-800C
1100-900C
1200-1100C
1000-800C
800-700C
Food
Composition
Fl3
Sw1(Bs1Fl1)
C2(Bs1Fl1)
Sb3Fl1
Bs1S2
Sb3S2
Final Check: The captain records the names of the minerals assigned to
each mineralogist. The captain asks each scientist to read off their
minerals’ temperature crystallization range and ion proportions.. Each
scientist records this information in their science notebook.
The Magma Cooling Table: The head volcanologist (teacher)
places the magma cooling table on the board.
Mark D. Greenman.
[email protected]
(781) 248-4952
The Experiment Begins
Mineral
Name
Quartz
Light Feldspar
Dark Feldspar
Olivine
Corundum
Hematite
Formation
Temperature
800-700C
1000-800C
1100-900C
1200-1100C
1000-800C
800-700C
Food
Composition
Fl3
Sw1(Bs1Fl1)
C2(Bs1Fl1)
Sb3Fl1
Bs1S2
Sb3S2
Not a Race: Each mineralogist must listen for the temperature prompts
from the temperature monitor. When taking ions ONLY take LEVEL
teaspoons of material from the bowls. A science team works cooperatively.
Forming the Minerals: ONLY make your assigned mineral when the
temperature is in the appropriate range. Once you have finished making
your mineral(s), seal the baggie and mix the ions VERY well.
Mark D. Greenman.
[email protected]
(781) 248-4952
Analyzing the Data
Mineral
Name
Quartz
Light Feldspar
Dark Feldspar
Olivine
Corundum
Hematite
Formation
Temperature
800-700C
1000-800C
1100-900C
1200-1100C
1000-800C
800-700C
Food
Composition
Fl3
Sw1(Bs1Fl1)
C2(Bs1Fl1)
Sb3Fl1
Bs1S2
Sb3S2
Q1: Iron and calcium (Sb and C) minerals versus potassium and aluminum
(Sw and Bs) minerals - Observe and record differences.
Q2: Comparing the amounts of each kind of mineral.
Q3: Conjecture on reason(s) for differing amounts.
Q4: Conjecture on what 2 things could be changed to result in differing amounts.
Q5: Conjecture on ease of separating ions that make up a mineral.
Q6: Two classification schemes to characterize your minerals into 2 groups.
Mark D. Greenman.
[email protected]
(781) 248-4952
Thinking Deeply
Mineral
Name
Quartz
Light Feldspar
Dark Feldspar
Olivine
Corundum
Hematite
Formation
Temperature
800-700C
1000-800C
1100-900C
1200-1100C
1000-800C
800-700C
Food
Composition
Fl3
Sw1(Bs1Fl1)
C2(Bs1Fl1)
Sb3Fl1
Bs1S2
Sb3S2
Q7: Speculate on how the mass per 30 mL cup (density) measure might be
a useful quantity.
Q8: Additional observations and conjectures.
Mark D. Greenman.
[email protected]
(781) 248-4952
Debriefing the Exercise
Strengths and weaknesses
M.A.S.T. Convention
Boxborough, MA - 2009
Mineral Formation
Critical Thinking and Collaborative Learning
Session 76
Presented by Mark D. Greenman
Einstein Fellow, National Science Foundation
[email protected]