Classifying Rocks and Minerals by Observable Properties
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Under Construction
AZ Science 7 Std, Strand 6, Concept 1, PO 1
Classify rocks and minerals by observable properties.
Classify rocks and minerals by observable properties.
A Middle School Level Website
Web-Science.net
Updated: 3/18/07
Links verified: 3/17/07
Links verified: 3/17/07
| "Look, Mommy! A pretty rock!" |
| Asbestos |
| Mercury |
Everything in nature is natural. It isn't always good for you. These two rocks are good examples.
They contain:
They contain:
reddish mineral: cinnabar (HgS)
| fibrous mineral: chrysotile (serpentine) |
There are many reasons to know about rocks and minerals. There are some that are
dangerous, whether we know about it or not. Others are valuable. Much of what we enjoy
comes from underneath the surface of our planet, whether it is metal or plastic. This is a big
difference between our modern industrial age and the past where much of what people used
was found or grown on the surface around them. It seems that each age of technological
advance was hinged upon something new found beneath the Earth's surface: Stone Age
(surface); Bronze Age (mined copper and tin); and the Iron Age (mined). Will people in the
future look back and call us the Petroleum Age (mined liquid; oil, gas, plastics, etc.)
dangerous, whether we know about it or not. Others are valuable. Much of what we enjoy
comes from underneath the surface of our planet, whether it is metal or plastic. This is a big
difference between our modern industrial age and the past where much of what people used
was found or grown on the surface around them. It seems that each age of technological
advance was hinged upon something new found beneath the Earth's surface: Stone Age
(surface); Bronze Age (mined copper and tin); and the Iron Age (mined). Will people in the
future look back and call us the Petroleum Age (mined liquid; oil, gas, plastics, etc.)
A Reason to Understand Rocks and Minerals through Study
Another reason to understand rocks and minerals is to have enough knowledge to make what is
called an "informed decision". An informed decision is making your own mind up with the facts
available. For example, do we need a new copper mine near our town? If we need copper and
want to continue to "consume" it, do we say "No!" Do we take the opinions of others because
we do not understand the issues? The democratic process requires that we (us, me) make an
informed decision, not delegating it to others.
called an "informed decision". An informed decision is making your own mind up with the facts
available. For example, do we need a new copper mine near our town? If we need copper and
want to continue to "consume" it, do we say "No!" Do we take the opinions of others because
we do not understand the issues? The democratic process requires that we (us, me) make an
informed decision, not delegating it to others.
| Rocks & Minerals |
What is a Rock?
What is a Mineral?
Just as if you are in Phoenix, you are in Arizona; however, if you are in Arizona doesn't necessarily mean you are
in Phoenix. The same is true of rocks and minerals. All minerals are rocks; however, not all rocks are minerals.
Coal, for example, is a rock, but is not a mineral.
in Phoenix. The same is true of rocks and minerals. All minerals are rocks; however, not all rocks are minerals.
Coal, for example, is a rock, but is not a mineral.
A mineral is described by the following traits:
Most minerals have chemical compositions known as compounds, or they contain two or more elements. For
example, the mineral cinnabar (displayed at the top of this page) is composed of two elements: mercury (Hg)
and sulfer (S). Cinnabar's chemical composition is HgS, or mercuric sulfide.
Some minerals are found occassionally in their elemental forms (one element; composed of only one type of
atom). These are antimony, arsenic,bismuth, carbon, copper, gold, iron, lead, mercury, platinum, and silver.
- It occurs naturally (not produced in a lab)
- It is inorganic (meaning not produced by some form of life)
- It is a solid
- It has a definite crystal form (same orderly array of atoms)
- It has a specific chemical composition
Most minerals have chemical compositions known as compounds, or they contain two or more elements. For
example, the mineral cinnabar (displayed at the top of this page) is composed of two elements: mercury (Hg)
and sulfer (S). Cinnabar's chemical composition is HgS, or mercuric sulfide.
Some minerals are found occassionally in their elemental forms (one element; composed of only one type of
atom). These are antimony, arsenic,bismuth, carbon, copper, gold, iron, lead, mercury, platinum, and silver.
A rock is a naturally occurring solid. With a few exceptions, rocks are composed of minerals. Rocks that are the
products of some form of life do not fit the definition of a mineral (see below). Volcanic glass, although
containing the same composition as a mineral, was cooled so quickly that no crystal structures were able to
form.
products of some form of life do not fit the definition of a mineral (see below). Volcanic glass, although
containing the same composition as a mineral, was cooled so quickly that no crystal structures were able to
form.
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