FOOLS GOLD
By Dave McCracken |
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It is not unusual for a beginner to wonder about the
difference between gold and the other materials found in a streambed or
lode deposit. Sometimes a beginner will puzzle over shiny rocks, and
quite often iron pyrites (fool's gold) are mistaken for the real
thing. In fact, this is so much the case that there is a story of an
entire shipload of iron pyrite having been shipped over to England during
the 1500's -- the yellow stuff having been mistaken for gold. So you can
understand where it gets the term “fool’s gold.”
Gold is a brassy yellow metal. Once you have seen a
bit of it in its natural form, you will no longer have much difficulty
distinguishing it from the other materials that are commonly associated
with it. Gold usually does not look anything like rock. It looks
like metal; gold metal. If you are just starting and have not yet had the
opportunity to see much gold in its natural form, there are three easy
tests which will help you va1idate your discoveries one way or the other:
Glitter Test: Gold does not glitter. It shines.
Sometimes it's bright; sometimes it's dull; but very seldom does it
glitter. The thing about fool's gold (pyrites or mica), is that because
of its crystalline structure, it is usually glittery. Take the sample and
turn it in your hand in the sunlight. If it is gold, the metal will
continue to shine regularly as the specimen is turned. A piece of fool's
gold will glitter as the different sides of its crystal-like structure
reflect light differently.

Hardness Test: Gold is soft metal, even more than
lead. It will dent or bend when a small amount of force or impact is
applied to it. Pyrites, mica and shiny rocks are generally hard and
brittle. Just a little amount of pounding will shatter them. Natural gold
almost never shatters!
Old-timers used to bite on a specimen to test if it
was gold. This is another way of testing the larger-sized specimens.
However, keep in mind that the larger-sized piece of gold is worth a
great deal and the resulting tooth marks could lessen its value. If you
find a piece of gold big enough for you to bite on, you will have little
doubt that it is the real thing, simply because of its nature and its
weight.
But if you are still uncertain of your find, you might
try using the sharp edge of a knife and gently press in on the specimen
in a place which is less likely to be noticed. If it's gold, an
indentation can easily be made into the metal with the blade of your
knife. You will not dent the surface of a rock or iron pyrites.
Acid Test: Nitric acid will not affect gold
(other than to clean it), whereas it will dissolve most of the other
metals found within a streambed.
Nitric acid can be purchased from some drug stores or
prescription counters. It can sometimes be found where gold mining
equipment is sold.

If you question whether your specimen is some kind of
metal other than gold, immerse it in a solution of nitric acid. If your
specimen is gold, it will remain rather unaffected. Almost any other kind
of metal will dissolve in the acid.
However, nitric acid will not affect iron
pyrites or mica (fool's gold), but those are brittle and will not pass
the hardness test.
CAUTION: Nitric acid can be dangerous to work
with. Precautions must be taken to prevent harm to yourself and your
equipment when working with it.
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