Lets Collect Rocks and Shells | Page 4

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.
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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 recover such metals from an average ton of earth. That's why metallic minerals are taken from concentrated deposits in mines.
Many valuable minerals are found in veins running through rock. Veins can be formed when: (a) mineral-laden ground water seeps into cracks, evaporates, and leaves mineral grains that build up into a vein; (b) hot water from deep within the earth fills cracks, then cools and deposits much of the material in solution as minerals in a vein--sometimes including metals such as gold and silver; (c) molten gaseous material squeezes into cracks near the earth's surface,