Lets Collect Rocks and Shells | Page 4

kinds of univalves and bivalves, but the latter will dig
themselves quickly out of sight--as far down as several feet. When you
see one going underground, don't dig directly over it--you might break
its shell. Instead, dig to one side, and break the mud or sand away with
your hands.
After you've had a good day's haul and a rest (you'll need one) you
must clean your shells. Put your tiniest, most fragile ones in rubbing
alcohol. Put the rest in a pot of fresh water and slowly bring it to a boil.
Let them cool in the water slowly to prevent the glossy shells from
cracking. When cool, your bivalves will be gaping open; simply scrape
them clean. Your univalves will be more difficult; remove the animal
with a crocket hook or other piece of bent wire, turning it gently with
the spiral; try to get it out whole to save yourself trouble. Save the
univalve's operculum and slice it off the muscle that holds it. It will
preserve indefinitely and is a valuable part of the shell.
Clean the shell's exterior by scraping it gently with a dull knife or nail
file, then soaking it in a Clorox solution (1 cup to 2 quarts water) for
two hours. Some will be covered with an ugly skin--scientists keep this
intact and you should try to. The best collection has two of each

species--one with and one without the epidermis.
After your clean shells have dried (in shade, not sun), go over them
with a rag dampened in light oil. This insures preservation and restores
their natural luster. Every three months or so, rub them with oil
again--their most delicate colors will remain brilliant for years. Don't
ever use shellac, lacquer or varnish. Get a reference book from your
library and identify your shells. Keep an account of when and where
you collected them.
Store your shells in closed containers to protect them from sunlight and
dust. Almost any set of small drawers or a cabinet will do. Matchboxes
or pillboxes are excellent for small specimens. For display purposes,
glass-covered cases are best to prevent handling of the shells. A shell's
beauty is often deceptive. Many unattractive and drab shells are worth
hundreds of dollars while the most colorful are frequently valued at a
dollar or less. The rarity of a species determines its value. A truly
valuable shell may come from deep, inaccessible waters or remote
lands--or it may be one of an extinct species. A Slit Shell collected 100
fathoms down in waters off the British West Indies is valued at $1000.
Another undersea treasure, the Glory-Of-The-Seas, was first found in
1771 and one time would bring the conchologist $1500. The greatest
rarities, however, are truly valueless and are not for sale.
. . .And there it is, the fascinating hobby of shell collecting. It's a lot of
work--but a lot of fun, too.
[figure captions]
Take a SIEVE. Or an orange sack. Besides carrying your shells, it may
help you catch them. A few pint BOTTLES will hold delicate ones.
MASK (or goggles) is essential for looking underwater. Bathing suit or
old clothes, of course. High shoes (or sneakers)--never go barefooted!
Heavy cloth GLOVES. Watch out for sunburn!
GIG or fish spear (if you're going South) to keep pesky crabs, sea
urchins off. CLAM DIGGING HOE or trowel for burrowing shells.
VINEGAR for first aid, in case you're stuck by urchin's spines.
CHISEL and HAMMER to get the clingers, spatula for frail limpets.
You may find other hardware handy, but these are basic.

NOW LET'S LOOK AT ROCKS

ROCKS ARE MADE OF MINERALS

Rocks, to begin with, are made of minerals. What is a mineral? The
definition may sound difficult--a mineral is a chemical element or
compound (combination of elements) occurring naturally as the result
of inorganic processes. But don't be discouraged. Things will clear up
soon.
The world contains more than 1,100 kinds of minerals. These can be
grouped in three general classes.
1. METALLIC MINERALS. These include things most of us would
think of if we were asked to name some minerals. Familiar examples
are copper, silver, mercury, iron, nickel and cobalt. Most of them are
found in combination with other things--as ores. We get lead from
galena, or lead sulfide. Tin comes from the ore cassiterite; zinc from
sphalerite and zincblende, or blackjack. Chromium that makes the
family car flashy comes from chromite. Many minerals yield aluminum.
Uranium occurs in about 50 minerals, nearly all rare. Twenty-four carat
gold is a metallic mineral. A 14 carat gold ring contains 14/24 or 58%
gold.
An average sample of earth contains 9% aluminum, 5.5% iron, .01%
zinc, .008% copper, .004% tin, .002% lead, .0005% uranium,
and .0000006% gold or platinum. It would be hopelessly expensive to