Download minerals - Ms. Sheehans Geology Class

Geology
Minerals Lecture
Name__________
Standards/Objectives:
- Define and describe minerals
- Describe the composition and structure of minerals
- Describe how minerals form
- Describe the physical properties used to identify minerals
I.
What is a mineral?
A. Mineral – is a naturally occurring, inorganic _______________ with a
definite _____________ composition and crystalline _________.
B. There are about ________ known minerals, ~______ are common.
C. They are the building blocks of __________.
II.
How do Minerals Form?
A. From the process of ___________________________– the
___________of a gas or liquid come together to form a solid mineral.
1. The atoms are arranged in an ordered three-dimensional array that
is ________________ in all directions.
2. The crystal _________ as more atoms are added onto the structure.
B. Minerals can form from a _____________ as it begins to cool below its
________________ point.
Ex: olivine and feldspar.
C. Minerals can form as liquids _________________ from a
__________________ (like the crystals you made in lab). This process is
called ________________________ (the minerals “fall” out of the solution
like rain falls out of the sky).
Ex: halite forms from salt lakes
D. Minerals can also form by _________________ - when a solid is formed
from a gas
Ex: sulfur forms from volcanic gas
III.
Chemical composition of minerals
A. Minerals are made of elements.
1. ___________ cannot be broken into ______________ substances
by ordinary chemical means.
a. There are _____ naturally occurring elements in Earth’s crust.
b. There are 92 naturally occurring all together on earth.
2. ___ elements make up 98% of the crust:
oxygen, _________________, aluminum, ______________,
_______________, magnesium, _______________, sodium
B. All minerals are _____________________ solids.
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A crystalline solid is a substance whose ___________ are arranged in a
regular, orderly periodically repeated manner.
C. Crystal __________ (flat planes) are the external expression of the
mineral’s internal ___________ structure (i.e., how the atoms are arranged).
IV.
What makes a mineral unique?
A. There are two fundamental _____________ that distinguish each mineral
from all others: _________________ ______________________ and
____________ __________________.
1. A mineral’s chemical _____________________ refers to the
________________ that form it.
Ex: Halite (NaCl), or table salt, is always made of a ratio of 1 sodium
(Na) atom and 1 chlorine (Cl) atom.
2. A mineral’s crystal ________________ refers to the internal
framework of the atoms that make up the mineral.
V.
Crystal forms and systems
A. The general shape of a crystal (cubic, octahedral, prismatic…) is called
its crystal ___________
1. If the minerals have enough space, they will form in their
crystalline habit.
Ex: quartz crystals in the shape of points.
2. If space is limited, they will have a _____________ form (can’t
see the crystalline habit).
Ex: mass of quartz where can’t see individual points.
B. Minerals are grouped into crystal ______________ based on their
symmetry (i.e., the angles their faces make to one another).
C. There are ___ crystal systems:
1. ___________
2. Tetragonal
3. ___________
4. Orthorhombic
5. ___________
6. Monoclinic
VI.
Physical properties – are used to identify minerals.
A. Cleavage – tendency of some minerals to _________ along a
____________. There is a difference between _________________
plane (how a mineral ____________) and crystal __________ (how a
mineral ___________).
B. ______________ – way in which minerals break other than cleavage
(e.g., they do not break along a plane). Types of fracture:
1. ________________ - smooth, curved surfaces
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2. ________________ - like ends of split wood
3. fibrous - similar to splintery, but with a softer appearance (like worn
cloth)
4. Irregular
C. _____________ – resistance of the surface of a mineral to
______________. Is controlled by strength of chemical bonds.
__________ hardness scale – compares the relative hardness of
minerals. They are arranged in order of ___________ hardness
(1 = soft and 10 = hard):
1. ________
2. Gypsum
2 1/2 Fingernail
3. ___________
3 1/2 Copper Penny
4. Fluorite
5. Apatite
5 1/2 Glass
6. Orthoclase feldspar
6 1/2 Steel
7. ____________
8. Topaz
9. Corundum
10. ___________
D. Specific gravity – ___________ of a substance relative to the weight of
an equal volume of __________.
It is a measure of _____________ (mass divided by volume or
D = m/V)
Ex: a mineral with a specific gravity of 2 weighs twice as much as the
same volume of water.
E. _____________ – most obvious property of minerals.
Not a reliable way to identify minerals. Remember the same mineral
can come in many different colors.
F. Streak – color of the fine _____________ of the mineral. More
____________ for identification than color.
G. _____________ – how mineral reflects ____________. Two main
categories:
1. metallic – looks like metal surface.
2. __________________ – if nonmetallic, must be classified as
a. vitreous – ________________
b. _____________ – whitish, pearl-like iridescence
c. Earthy or dull
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d. ______________ –like amber or rosin
e. greasy – looks like it’s covered by thin layer of oil (rainbow of
colors).
H. ______________ – resistance of a mineral to ______________
1. Brittle – breaks and powders easily
2. ______________ – can be hammered out into thin _______
3. Sectile – can be cut into thin shavings with a knife
4. _______________ – can be drawn into a ____________
5. Flexible – bends but does not resume original shape (copper)
6. _____________ – bends and regains original shape (mica)
I. Other properties
1. acid reactivity – effervesces (___________) with hydrochloric acid
(HCl)
2. ________________ is attracted to a magnet or picks up iron filings.
3. fluorescence – emits visible light when exposed to UV
4. phosphorescence – continues to emit light after external source is
taken away.
VII. Mineral classifications
A. ________________ – minerals containing silicon (Si) and oxygen (O).
Most abundant in Earth’s crust. Make up 95% of crust.
B. ________________ – contain carbon (C) and oxygen.
C. ________________ – composed of oxygen and metals.
D. ________________ – contain sulfur (S) and metals.
E. ________________ – made up of sulfate (SO4)- and metals.
VIII. Rock forming minerals: common minerals that make up rocks.
A. Silicates – are the most common minerals that make up rocks.
1. _______________ – most abundant mineral, ____% of Earth’s crust.
a. orthoclase feldspar – contains potassium (K)
b. plagioclase feldspar – contains calcium (Ca) and sodium (Na)
2. _______________ – 2nd most abundant mineral, SiO2
3. _________________ – Ex: augite
4. Amphibole – Ex: hornblende
5. Mica – Ex: _________________
6. Clay minerals – Ex: kaolinite
7. _______________

L. Brown
Updated November 2010
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