Directed Reading Handout on Mineral Formation
Name _____________________________ Date ______
Part 1. Here is a list of descriptions (a-f) of six ways minerals form. Look at the diagram in the reading (pp. 1213) that shows important clues about each. Write one word from the word bank that you think matches the
description the best.
Word Bank Name : Evaporites, Precipitates, Metamorphics, Hydrothermals, Pegmatites, Plutons
Surface or Deep: From the diagram decide whether this type of mineral would form at or near the earth’s
surface or deeper underground (S for at or near the surface. D for deeper underground.)
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Description
Word Bank Name
a
Minerals that form when pressure and heat
cause rocks to bend deep inside the earth
b
Minerals in hot ground water solutions that
crystallize in cracks in the bedrock
c
Minerals that are left behind when water
evaporates out of a shallow lake.
d
Minerals that crystallize as magma rises
upward in the presence of hot fluids
Surface or
Deep
e a. Minerals that crystallize when a large body
of magma cools very slowly underground.
b.
Minerals that settle out of water either in
caves or the bottom of a lake or sea.
f
Critical Thinking:
Find answers in the reading and picture description.
1. Suppose you find a mineral crystal that is as tall as you are. What kinds of environmental factors would
cause such a large crystal to form? (Look through Diagrams of Mineral Formations p.12-13)
2.
In some environments it is so dry that lake water evaporates until it is a dry lake bed. To find a mineral
such as gypsum in a dry lake bed, would you look near the surface of the earth or deep underground?
3. Which of the following is NOT important in the formation of minerals? (circle your answer)
A. heat and pressure
B. underground volcanic activity C. presence of ground water
4.
D. wind
Minerals can form underground in these teardrop-shaped formations called _______________________
Part 2. Mineral Detective: Choose the name of a mineral in Column B that best matches the description
of how it formed in Column A, and write the corresponding letter in the space provided in Column A.
Column A
Column B
____ 1. Forms from slowly cooled magma that solidifies into a pluton
a.
____ 2. Forms in veins from heated ground water near the earth’s surface.
b. Garnet ___
____ 3. Forms pegmatites in the presence of magma and hot fluids.
c. quartz ___
____ 4. Forms in metamorphic rock under great pressure
d. gypsum ___
____ 5. Forms from materials in cool surface water that evaporate
e. calcite ___
____ 6. Forms precipitates in caves and at the bottom of lakes and seas.
f. Topaz ___
Gold
___
7. What is the difference between a pegmatite and a pluton?
8. Concept Mapping: Use the following terms to complete the concept map below: Lakes and seas, cooling,
chemical composition, evaporates, hot water solutions.