There are several minerals that can be confused with gold, especially when in very small
pieces. Small pieces of mica are especially confusing since they can have a yellowish
sheen and are very common just about everywhere. The very first time that I panned for
gold I was fooled by mica. Being very light, I should have suspected it was not gold as
the flakes floated out of the pan. As noted on the Gold Facts page, gold is much denser than mica. This page
was started as a response to an e-mail question.
Here are some simple tests.
For flecks in rock, a small piece of the rock needs to be ground up to free the
flecks. Best done with a mortar and pestle but can be done carefully with a vice
or hammer with some way to contain the resulting particles.
- Put some of the sand (or ground rock) in a gold pan, pie pan, or shallow dish with
some water. Make sure the pan or dish doesn't have any oils as this can cause
small gold flakes to float.
I have seen small gold float in a pan due to skin oils but with a slight tap on
the particle it will drop to the bottom (like a rock) and behave normally.
If this is a problem, a couple of drops of detergent in the pan will break up the
oils as well as the surface tension of the water.
- As you swirl the water and the pieces move, gold will shine but not sparkle or
twinkle. Pyrite and mica will sparkle. Gold, being soft, will wear into a
rounded or contorted shape, without cleavage planes that give a highly reflective
appearance in any one direction. However mica, pyrite, arsenopyrite and
chalcopyrite are all brittle and wear differently, usually having areas
that will reflect light better than others, producing a twinkle.
Mica forms sheets and wears as small flat pieces that can be
highly reflective in one direction and not in others.
I watch carefully when panning as this is a good test.
- Gold does not change much in brightness between sun and shade. Examine the
material in the pan in sun and then in shade, you can use your hand to shade
the material. If there is a sharp change in brightness, it is probably not gold.
I sometimes use this test myself when panning.
- Also note that gold does not move easily, compared to other minerals, in a pan of
gently swirling water. Flatten some small lead shot so that it doesn't roll easily and
put it in a pan with what you suspect is gold. Since gold has a specific gravity
of 15.6-19.3 (depending on purity and attached minerals) as compared to 11.3 for
lead, 5.0 for pyrite and 2.7-3.4 for mica, any minerals that move much easier than
lead are not gold while those that do not move as easily have a good chance of
being gold. For this to work well, the lead shot should be similar in size to
the particles in question. Lead is very soft so it can be cut up or shaved into
very small pieces. By the way, lead shot is used for panning practice as once
you get to the point of not losing any lead while panning, you will probably not
lose any gold. If one does much panning anywhere, you will end up with some
lead shot as it seems to be in all the streams and washes due to hunting over
the years. Gold panning contests sometimes use lead instead of gold.
- Use an eye dropper to pick up a small pieces and then slowly squeeze them out
near the top of a small vial or glass of water. If they sink like a rock, very
quickly, even the smallest ones, then they are not mica. It is amazing how
fast even the tiniest pieces of gold sink in water. Almost too fast to watch
for very small pieces. I watch this all the time when I am transferring small
gold from my pan to a small vial (about 1 1/2 inches tall and about 1/2 inch
in diameter). It doesn't take much water to see this effect.
By the way most of the gold I find can be picked up by a standard eyedropper.
- Look at the bigger pieces with a magnifying glass. Again if you seen a crystal
structure or flat surfaces, then gold is unlikely. This is especially true if
you see a flat surface with striations (minute parallel grooves) as this is
usually indicative of pyrite. (Crystalline gold usually comes from mines.)
- The ultimate test is to hit a bigger piece lightly with a hammer on a flat hard
surface. If it breaks it is not gold. If it flattens, it is gold. Of course this
ruins the value of the gold as a specimen so this is a test of last resort for
larger pieces (those that can be easily picked up with the fingers). I don't
use this test, for obvious reasons, unless I am darn sure it is not gold.
A good test is to look at the streak of a mineral. This is the color observed when the
mineral is crushed into a fine powder and then placed on a white sheet of paper. A more
convenient method is to rub the mineral across a tile of unglazed white porcelain, called
a streak plate, and noting the color of the streak. See the following chart. Note that
this test can only be used on minerals that do not exceed the hardness of the streak
plate, about 6 1/2.
Selected Minerals and their streak color
||yellow or gold|
There are tests using acids but the above are the easiest with little or nothing
to buy, are safer and should be enough. Especially if you are only trying to
differentiate between gold and other minerals.
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This page was last updated on 25 September 2008.