are a few things that everyone who has done any prospecting or
mining has learned to hate. Floured mercury, lack of water, and
black sand. O.K. there are a few others but black sand is in the
same class as floured mercury. It is very difficult to deal with.
It is very heavy. Its density is about 5. That is it is about 5
times heavier than water.
average "dirt" with small stones etc has a density of
about 2-21/2. Gold has a density of 19.3. The thing that drives us
all a little crazy with black sand is that it is relatively easy
to separate the "dirt" from the gold but most of us find
it much more difficult to separate the gold from the black sand.
There are hundreds of methods to accomplish this job. Probably
just about, as many methods as there are miners.
Central America the "oreros" dont use a pan like
anything that we have. This pan or "catea" is hand made
from the top of a 55 gallon steel barrel. They dig a shallow hole
in the ground and put the steel over it. They hammer the steel
disc with a rock until it is in the shape of a "wok", a
Chinese frying pan. They then pound a "dimple" in the
bottom/center of this pan. The dimple is about 1 inch in diameter
and maybe 3/8 inch deep. With this device the locals can reduce a
catea (maybe three of our pans) to an amount of gold/black sand
that fills the dimple in a matter of a minute or two. I was once
told by an orero who was trying to use a plastic "Garret"
pan that he didnt think much of it. In fact, I remember his
exact words. He said "con esta catea, me muere de hambre".
With this pan, I would die of hunger. At the end of the day, like
us, they gather all their concentrates and separate the gold from
the black sand. They simply re-pan it. When they get to the last
dimple-full of concentrate they do something that I have never
seen before. They spit in the pan. Then with a finger, they work
the saliva into the concentrate and continue to pan. For some
reason unknown to me, the black sand seems to aggregate in the
saliva. It just sort of balls up apart from the gold. They
eventually discard the saliva ball and leave the gold just lying
there in the dimple. Believe me, it works. My efforts to use this
method were not particularly successful. It mostly resulted in
rails of laughter from all the "good ol boys " who were
watching with intense interest. So far I have been unable to get
them to explain to me how they do it. After all, they have a ball
watching me try. It makes their whole day.
watch these oreros pan is something not to be forgotten. If the
best panner in the US were to go head to head with these guys for
a day, no contest. After an hour or two you would be so far behind
that that you would want to just disappear into the jungle. It is
downright embarrassing. I know how to pan with these devises, but
I just dont have the muscle to do it for more than one pan.
That catea with at least three of your heaping pans in it is
heavy. Yet, they can do it all day just as fast as you can fill
the pan with a shovel. These guys are not normal. They are
animals. I know one of these guys named "shorts" who can
carry my Keene dredge consisting of 8 hp engine, pump, and
compressor (100 lbs) on his shoulder up a 30 degree mountain slope
for four hours without breaking stride. When he told me that he
could do it, he was sort of embarrassed to tell me that he would
like to have something to put on his shoulder to cushion it. He
said that metal sort of "cut" his shoulder after awhile.
Think you are tough? You just dont have the proper
of that. We started out to talk about black sand. So, what is
black sand? Does anyone know? Are you sure? Usually we say that
black sand is made up of two kinds of iron oxides, magnetite and
hematite. That is pretty much true.
Magnetite and Hematite are oxides of Iron. These are rather
complex inorganic compounds that can occur in various forms. They
can be crystalline or amorphous i.e. no organized structure.
Hematite almost always occurs in a crystalline form. In this
highly organized state it is extremely resistant to reaction with
most chemicals. It would be much better for us if they were all
amorphous, as they would then present no great problem; we would
just dissolve them. However, the fact is that the stuff that gives
us backaches is mostly crystalline forms.
magnetite is called ferrosoferric oxide and has a formula Fe3O4.
It contains 3 atoms of Iron and 4 atoms of Oxygen. It melts at
1538 C and has a density of 5.2. It is destroyed by heating in the
presence of Oxygen. It can be dissolved by strong acids, but it is
slooow. It is, of course, magnetic.
not going into all the methods of removing magnetite from
concentrates. You guys probably know more ways than I do. I
normally use the following method and it seems to work pretty good
if you are careful.
handful or two of concentrates and put them in a plastic pan,
cover with a generous amount of water. Now get a good magnet, not
one of those your wife sticks on the refrigerator. Put it in a
plastic bag and carefully pass it around in the pan above the
concentrates. DO NOT STIR THE CONCENTRATES WITH THE MAGNET! The
trick is to make the magnetite jump up through the water to the
magnet. Remove the magnet from the pan and stir, then repeat until
no more magnetics can be removed. Do not discard the magnetite.
Keep it so that you can examine it later to see how careful you
sesquioxide. This is another oxide of Iron, also known as Jewelers
Rouge. It is not so chemically resistant as Magnetite and can
usually be dealt with by treatment with strong acids, bases,
Clorox, etc. Its chemical formula is usually written as Fe2O3. Two
Irons and three oxygens. If you heat Magnetite at fairly high
temperatures in the presence of oxygen you will end up with
on occasion, had good luck treating hematite with concentrated
sulfuric acid. Give it a try but be CAREFUL and read the page on
acids and bases first.
fact, try this first just so you understand what sulfuric acid can
do to you. Take a small Pyrex vessel; put about an inch of common
sugar in it. Now slowly pour in enough concentrated sulfuric acid
to just wet it. Do this outside or in a place where nothing can
get away. Now just stand back and watch it for a few minutes.
Think what that could do to you, and, I guarantee that it will do
the same to you. No, Im not going to tell you what happens.
Try it, you will never again treat concentrated sulfuric acid with
is a metal that no one knows much about, Tellurium. Go to "links",
"periodic table of elements", and you will find all the
chemical characteristics of this element. It is a metal with a lot
of chemical properties similar to gold. No, its not a
precious metal, but it does have a unique property. It forms
natural salts (complexes) with gold. Some of the most valuable
gold ores that exist are in the form of Tellurides. Yeah, I know,
someone told you that gold was inert, it doesnt combine with
anything in nature. It only occurs as the elemental metal, GOLD.
Well, as usual, they told you wrong. Im sure they believed
it, their best buddy told them, so it must be true. The buddy only
had hearsay evidence, old wives tales. We Basement Chemists only
believe the tales that can be substantiated. Sure we all know that
there is gold dissolved in sea- water as the salt, gold chloride.
True, but the amount is so small that, for our purposes, it can be
ignored. We aint gonna get rich on that.
someone is going to say, " gold comes, in nature, combined
with mercury, silver, copper, etc, I find it all the time. These
amalgams that we all find once in awhile, are not "combined".
they are not another chemical. They are not salts of gold,
mercury, silver, or copper. They are simply mixtures of gold,
silver, copper, and mercury. They have not chemically reacted to
form another compound.
what the hell is a Telluride anyway? Well, as Basement Chemists
you should have caught on by now that when a chemical name ends in
"ide" it means that it is a salt. The things are
chemically combined, not just mixed or dissolved in each other.
Hydrogen sulfide is not hydrogen dissolved in sulfur. It is
hydrogen reacted with sulfur to produce a completely different
chemical. If not, you could simply warm the hydrogen sulfide and
it would boil off hydrogen and leave sufur behind. It dont
work that way. They are reacted to form a chemical that is not
hydrogen nor sulfur. Its a completely different thing.
gold, and silver (and other metals) can react to form Tellurides.
Why are they not called "goldides"? Dont know. I
think it just dont sound as good. Actually, it is because
you can have tellurium/silver, tellurium/gold, or
tellurium/silver/gold. You cannot have silver/gold. That is an
amalgam, a mixture, not a compound.
are a few tellurides that are of interest to prospectors/miners.
is the name given to a telluride that occurs in certain areas as a
brown/black, friable material that if you pan it out might very
well show no gold at all. However, this stuff can be the "Elvis
Pressley" of gold ores. All you guys have heard of a place
called "Telluride" Colorado, right? The reason they
called it that was that they had deposits of tellurides that were
yielding so much gold you couldnt believe it. Calaverite is
the ore that you want to find. It can assay from 20- 70% gold and
it is easy to recover. You and I have probably walked on it, dug
it, looked at it, thrown it away, and moved on to better spots.
The problem is that it doesnt look like gold. You might not
see even a color, or as we say here "ni un ojo de zancudo"
(not even a mosquito eye). This ore is metallic and is amenable to
amalgamation with mercury. It is very heavy and can be caught in
sluices etc. It, however, does not look like gold, is not yellow,
and is usually tossed out with the black sands. It appears more
like gold/mercury amalgam than gold but it is not quite that
would probably be worth your time to visit a nearby university etc
and ask them to show you some samples of Calaverite, just so you
know what it looks like. Maybe they would give you some so that
you would have it to compare with any suspect ore. This ore is not
one that you would want to miss. A little deposit of this stuff
could make your whole year.
should get into a deposit of this material, be careful. Dont
throw anything away until you are sure it has no gold in it. If
you should discard a small percentage of Calaverite, at 60% gold,
it could be big bucks. Send it to me, Ill be happy to deal
with it. Ill even pay shipping charges.
another telluride of silver/gold. Not so significant as the above.
telluride of gold and silver. It can assay as high as 20% gold.
telluride that is mostly silver. Silver content is usually twice
that of gold.
Petzite. Usually about 60% silver
sulfide is a reduced salt of sulfur. Like copper sulfide, CuS2. An
oxidized salt of copper and sulfur would be Copper sulfate. CuSO4.
Remember about redox? Addition of an oxygen oxidizes the compound.
Anytime you see the ending "ide" it means that the
compound is in its "reduced" form. If you see the
ending "ate" it means that it is in its oxidized
form. You see, us scientific types have our own language so that
we can talk without having to explain at every step what we mean.
Hang with me and Ill tell you a little about this language.
Hell, it aint no harder than learning Spanish.
can ruin your whole day. They coat almost everything with surface
of sulfide that will prevent you from amalgamating, reacting with
cyanide, or dissolving in solutions of halides. If you have a
little piece of silver, a little hydrogen sulfide from the local
volcano, you will have a piece of silver with a coat of silver
sulfide on it. This coat will prevent you from dissolving it in
cyanide or any other.
for us sulfides are relatively unstable. Want to destroy a
sulfide? Its not too difficult but one that I am afraid most
folks ignore. HEAT IT! Almost all sulfides will dissociate with
heat. That is, if you heat a sulfide in the presence of oxygen you
will boil off the sulfur as either sulfur dioxide or as hydrogen
sulfide. If you heat some ore that you suspect of having sulfides
present you will smell a rather unique odor.
any of you ever been to a "beer and egg party"? A keg of
beer and a great quantity of hard-boiled eggs? The next day you
are a bit bloated, gaseous, or in scientific terms, "flatulent".
When you, as the English say, "pass wind", this is the
odor of sulfides being dispelled from the heated ore. When the
odor of sulfur is no longer apparent, you can continue to your
time-honored way to deal with sulfides is to boil them off with
get some roofing metal, get it up off the ground with a few rocks
etc and build a good fire under it. Spread your material on the
metal and let it cook. When you dont smell anymore sulfur,
HEAT IS CHEAP, USE IT!