|
Mohs Hardness Scale
Hardness is identified numerically by comparison
to standard
minerals on the Mohs Scale, from 1 (softest) to 10 (hardest) |
|
1. Talc
2. Gypsum
3. Calcite
4. Fluorite
5. Apatite
|
6. Orthoclase
7. Quartz
8. Topaz
9. Corundum
10. Diamond
|
Three Kinds of Rock
Sedimentary Rocks
For thousands, even millions of years, little
pieces of our Earth have been eroded - broken
down and worn away by wind and water. These
little bits of earth are washed downstream,
where they settle to the bottom of the rivers,
lakes, and oceans. Layer after layer of eroded
earth is deposited on top of each. These
layers are pressed down more and more through
time, until the bottom layers slowly turn
into rock.
Igneous Rocks
Igneous rocks are called fire rocks and are
formed either underground or above ground.
Underground, they are formed when the melted
rock, called magma, deep within the earth
becomes trapped in small pockets. As these
pockets of magma cool slowly underground,
the magma becomes igneous rocks.
Igneous rocks are also formed when volcanos
erupt, causing the magma to rise above the
earth's surface. When magma appears above
the earth, it is called lava. Igneous rocks
are formed as the lava cools above ground.
Metamorphic Rocks
Metamorphic rocks are rocks that have "morphed"
into another kind of rock. These rocks were
once igneous or sedimentary rocks. How do
sedimentary and igneous rocks change? The
rocks are under tons and tons of pressure,
which fosters heat build-up, and this causes
them to soften and change.
Items Made From Rocks and Minerals
Some everyday items that are made from or
consist of rocks or minerals include jewelry,
table salt, chalk, pencil lead, coins, wire,
cans, safety pins, scissors, chewing gum
wrappers, roads, and glass. There are many,
many others.
Crystal Garden
Mix the water, ammonia, bluing, and salt
in a bowl. Put the charcoal in a pie pan.
Pour the liquid over the pieces of charcoal.
Put the pie pan in a warm place where the
water will evaporate quickly. When the water
has evaporated, a "garden" of crystals
will have grown!
Resources
Check the children's section at your local
library for information on geology. If your
have access to the Internet, try using various
search engines to look for the information
you need.
A field trip to a museum can provide an excellent
hands-on experience with rocks and minerals
in your local community.
|