Lets Collect Rocks and Shells | Page 7

but
should be rinsed with alcohol. A coat of clear lacquer will protect some
samples against dirt.
Arranging Your Collection
Put a spot of enamel on the specimen. Write on the spot--in India ink--a
catalog number and have this number refer to a card in a file drawer.
The card should list date, place found, identification of specimen, etc.
Group your samples: metallic minerals, semiprecious stones,
nonmetallic minerals. Display them on a shelf, or buy or build a
mineral cabinet with partitioned drawers. For smaller samples, use a
Riker mount with a glass top.
[figure captions]
A common rock
Here's the equipment to take: newspapers for wrapping samples,
notebook and pencil, geologist's pick, cold chisel, magnifying glass,
compass, heavy gloves, a knife, and a knapsack.
What Do I Have?
How do you identify specimens?
Get books and magazines on rocks and minerals. Many have colored
pictures that help.
But identification is best made by noting the physical characteristics of
the rock or mineral. For minerals, there's a hardness scale in which a
mineral of the higher number can scratch a mineral of the lower
number but not be scratched by it. The scale is: 1) talc; 2)gypsum; 3)
calcite; 4) fluorite; 5) apatite; 6) orthoclase; 7) quartz; 8) topaz; 9)
corundum; 10) diamond. Remember it by this silly sentence: "The girls
can flirt and other queer things can do."
When on a trip, remember that a fingernail has a hardness of 2.5; a
penny, 3; a knife blade, 5.5; and a steel file, 6.5. Use these to scratch
your sample and you can get an approximate idea of its hardness.
You can buy a set of hardness points. They're pointed pieces of
minerals set in brass tubes, each marked with its hardness scale. The set
costs about $30 (half that if you assemble your own).
Other tests for identifying minerals include specific gravity (weight of
mineral compared to the weight of an equal volume of water), optical

properties and crystal form, color and luster. Minerals differ in
cleavage and fracture (how they come apart when cut). They leave
distinctive streaks on unglazed porcelain. Some are magnetic, some
have electrical properties, some glow under ultraviolet or black light,
some are radioactive, some fuse under a low flame while others are
unaffected. Many studies with the dissolved mineral can identify it
beyond doubt.
But most of these are too complicated for the beginner. As you read,
look at pictures and samples, and talk with other rockhounds or leaders
of mineralogy clubs, you'll get better at identifying rocks. Museum
experts and your state's geologist can help, too.
[figure captions]
Specific gravity balance
Blowpipe analysis

GEMS FOR THE LUCKY FEW

If you're lucky, you'll find gems or semiprecious stones. Gems are the
finer, more crystalline forms of minerals which are ordinarily less
beautiful and spectacular. The true gems are diamonds, emeralds,
rubies and sapphires. All others are semiprecious and ornamental.
Diamonds are pure carbon, but did you know that rubies and sapphires
are corundum minerals--rare forms of alumina. In slightly different
form, they'd turn up on emery paper.
Other stones you might find are the quartz gems: rose quartz, amethyst,
rock crystal, agate, jasper, bloodstone. Or opaque gems such as jade,
moonstone, lapis-lazuli, obsidian, and turquoise.
You don't have to find them. You can buy gems in the rough or in
blanks, then cut and polish them to make your own jewelry or
decorations. This takes practice, plus a cutting and polishing outfit,
wood vise, maybe a diamond wheel. (Or you can join a lapidary club
that might already have the equipment).
First learn to make cabochons--stones with round or curved surfaces.
Then try cutting facets (or faces) in transparent gems. Learn by reading,
working with an expert, trial and error. Making jewelry is fun, and
collecting gems is as interesting as collecting rocks and minerals; it
brings the world into your home. From the West come agates, jaspers,

petrified woods; from the East, colorful marbles, serpentines, granites.
Alaska, Idaho, Connecticut or Austria will yield dark red garnets. Fine
moonstones come from Ontario; quartz crystals from Hot Springs,
Arkansas, can be compared with similar ones from the Swiss Alps or
Brazil.
Rock collecting is a hobby you can tailor to your taste. But whether you
concentrate on an area close to home or travel across whole continents,
you'll find that the pleasure and knowledge you gain from your
collection are matched by the fun and adventure of the search.
[figure captions]
Drop sticks to hold stones
Diamond cutting wheel

[BACK COVER]

A Brontosaurus
Shell Oil Company
Revised 8/88

End of Project Gutenberg's Let's collect rocks & shells, by Shell Oil
Company
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