Date
HARDNESS
•MINERAL
• • • • • ••
• •• • • • • • • • • •• ••• • • • • • • • • • • • • • • • • •
MINERAL-HARDNESS TEST PROCEDURE
1. Start with your fingernail.
2. Try to scratch all four minerals with your fingernail.
3. If your fingernail scratches the mineral, write "yes" in the chart.
4. If your fingernail does not scratch the mineral, write "no" in the chart.
5. Follow the same procedure with the aluminum nail and then with the steel paper
clip.
TOOL
MINERAL
Fln~mail
Aluminum
(nail)
Steel (paper
clip)
How many
tools could
scratch this
mineraI?
,
1
2
,
3
4
List the four minerals from
hardest to softest.
Hardness information:
Quartz is hardest.
Gypsum is softest.
Fluorite is harder than calcite.
FOSS Solid Earth Module
@ The Regents of the UniVeesity of Cafifcnja
Can be duplicated for classroom or workshop
I!ISe.
230
Investigation 2: Scratch Test
Nb. 8-Scfeooe,
Notebook
MINERAL HARDNESS
• • • • • • • • • • • • • • • • • • • • • • • •• • • • • • • • • • • • •• • • •
MINERAL-HARDNESS
TEST PROCEDURE
1. Start with your fingernail.
2. Try to scratch all four minerals with your fingernail.
3. If your fingernail scratches the mineral, write "yes" in the chart.
4. If your fingernail does not scratch the mineral, write "no" in the chart.
5. Follow the same procedure with the aluminum nail and then with the steel paper
clip.
DATA
TOOL
'tJ
-
ftj
e
'ceu
-
CI)
E
~
c
'E~
-..
,e-
c-:;
'i
0
..c
Co)
CI)
ll)
U
'0
'E
CI)
>e
cu
:E
a.
cu
a.
-.•..
GiCI)
.•..0
II)
;:
••
.•..(Jcu
0
Co)
.c:
E
-
."
i:i:
Ci
0
calcite
no
yes
yes
2
quartz
no
no
no
0
3 gypsum
yes
yes
yes
3
4f1iuori+e
.
no
no
yes
1
c
Mineral
1
2
LIST THE FOUR MINERALS
HARDEST TO SOFTEST.
quartz
fluorite
calcite
gypsum
FROM
:z::
II)
ES4b. Students know how to identify common rock-forming minerals (including quartz,
calcite, feldspar, mica, and hornblende) and ore minerals by using a table of diagnostic
,l)roperties.
eologists use a number
scale to describe mineral
hardness. Friedrich Mohs
(1773-1839) came up with the scale.
Mohs was a German scientist who
studied .minerals. He knew that
some minerals could scratch others.
If one mineral could scratch
another, it must be harder than the
mineral that was scratched.
The Mohs hardness scale goes
from 1 (soft) to 10 (hard). The
.meral talc, the softest mineral,
has a hardness of 1. Diamond, the
hardest mineral, has a hardness
of 10. All the other minerals fall
between talc and diamond. These
ten minerals represent the ten levels
of hardness.
Between the hardest and softest
minerals are all the other minerals.
Minerals with higher numbers on
the Mohs scale will scratch minerals
with lower numbers. Calcite
can scratch gypsum, but it cannot
scratch fluorite. Quartz can
scratch feldspar, but it cannot
scratch topaz.
Mohs hardness scale
10 Vialftot1d
,
9 Corut1dulft
~
I
8 ropaz
7 Quartz
6 Feldspar
5 Apatite
4 Fluorite
3 Calcite
2 Gypsulft
1 rale
I
195
___
II
The minerals at the hard end of the Mohs scale are called
gems. Gems are hard minerals that can be cut into beau . - ,
shapes. Because they ate hard, they last a very long time.
People have identified gem minerals with the months of tk ~
These gems are called birthstones. At one time, people ~
birthstones could protect, heal, or bring good luck. Some
birthstones were thought to have magical powers. Which of
beautiful minerals is your birthstone?
January: &arnet
Often colored red, garnet crystals form easil:
rock. Long ago, people believed a garnet wo
protect its owner from wounds.
February: Amethyst
Amethyst is a form of quartz that is purple.
Amethysts were once thought to keep soldiers s
in battle.
March: Aquamarine
The mineral beryl forms crystals of different
colors. Blue crystals are called aquamarines.
Aquamarines were supposed to bring good lu
to sailors at sea.
II:
"".
er-
"
'
:. ,::" .1-:,
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April: Oiamon~
It takes extreme heat and pressure to turn
carbon into diamond. Diamond is the harde:
natural substance in the world. Some people
believed a diamond would give them strength
May: Emerald
Unlike other gems, emeralds are not found
washed into streams. They must be mined fr
other rock. It was said that an emerald place
under the tongue lets you see the future.
June: Alexandrite
Along with pearl, alexandrite is the birthstom
for June. This mineral is both rare and uniqui
In natural sunlight it looks green. But whee i
lit by a lightbulb, it looks red.
July: Ruby
Most rubies are found in streambeds or under
soil. It was thought that a ruby turning dark
warned its owner of danger.
August: Peridot
Green and yellow-green peri dots are forms of
the mineral olivine. They can be found in lava
flows and in meteorites. Peridot is the only gem
that may come from outer space! Peridot was
said to give its wearer dignity.
I September: Sapphire
Both sapphires (blue) and rubies (red) are
crystals of the same mineral, corundum.
Legend says a sapphire will make a foolish
person WIse.
lctober: Opal
Opals can be clear, cloudy, or opaque. Opals of
good quality may show rainbowlike colors. The
Romans wore opals for love and hope.
November: Topaz
Pure topaz is colorless. Impurities can make
topaz yellow, blue, green, orange, or pink. In
the Middle Ages, topaz was said to improve the
mind. The largest known topaz crystal weighs
271 kilograms (596 pounds)!
Oecember: Turquoise
Bluish gre-en turquoise is an opaque mineral that is
rarely found in crystal form. Native Americans of
the Navajo tribe believed a turquoise thrown into
a river with a prayer would bring rain.
)
Name:
_
J
Date:
_
Minerals/(jemstones
What I wonder before I read ...
What I wonder as I read...
What I am confused about. ..