Hi Orchid,
I just acquired a bit of gold from a local miner here in Alaska and
I’m thinking using it in it’s unrefined state to make 22k
(aproximately) granules for accenting my argentium filligree pieces.
Also I would like to roll some into bezel strip for stone setting.
The gold has been melted and poured into water but otherwise is not
refined. The gold from this mine has been assayed at over 22 karats.
So is it ok for me to stamp it 22k? Are there any problems with
fabricating with unrefined gold, as in brittleness or porosity?
Thanks for your help.
Douglas
You must assay it to legally stamp it! Most placer gold tests at
about 90% right out of the ground. or streams. but one can’t presume
it’s x karat without testing it! Consider taking it to a local
jewellery store that uses XRF testing to buy gold from the public- it
will give you a read in seconds that will tell you the composition
and karat if you are not able to use an acid test and stone well
yourself.(it takes a bit of experience to get it right particularly
testing between 18-22 karat gold as sometimes the acids are old and
have sat in a plastic dropper bottle too long or test, stones aren’t
as clean as they should be which throws the entire process off or the
reader is simply not experienced and everything appears the
same)…rer
I also live in Alaska and use raw placer gold often, particularly for
bezels. Years ago I bought maybe 20 ounces of placer gold from a mine
up north of Fairbanks somewhere. It is probably 22k or so. It works
beautifully, is very malleable, rolls and draws nicely etc. Has an
interesting characteristicthough. It work hardens fairly quickly. On
the other hand, I once bought afew ounces of placer material, also
high karat, which no matter what I do with it, cracks and crumbles
and can’t be worked. I’ve tried melting it andpouring it in water,
making an ingot and rolling it several times but no luck. Although
both batches are about the same purity, I suspect that whatever the
impurities are, they differ between the two batches. I would suggest
you just experiment with yours and see what they will do.
Jerry in Kodiak
On the other hand, I once bought afew ounces of placer material,
also high karat, which no matter what I do with it, cracks and
crumbles and can't be worked. I've tried melting it and pouring it
in water, making an ingot and rolling it several times but no luck.
Although both batches are about the same purity, I suspect that
whatever the impurities are, they differ between the two batches.
Lead contamination is one thing that will cause cracking. I once had
a refiner send me 100 ounces of sterling, contaminated with lead.
Cast pieces would act like dry pasta with little pressure it would
crumble into pieces.
Richard Hart G. G.
Denver, Co.
I melt raw placer fines to use fabricating high carat jewellery, and
have found that some gold works beautifully and others not at all.
The purity of the gold is not a factor; some high purity gold does
not work, while some lower purity gold does. I have been told that it
is the presence of either zinc or lead in the natural alloy which
renders it unworkable. I have learned to melt a sample and try to
roll it - either it works or not. If not, it cracks. Although, a
German goldsmith taught me that you can sometimes “heal” the cracks
if it is not too bad - that is heat the cracked areas just to melting
when annealing. Better to work with gold that doesn’t crack, if
possible.
Leslie Chapman
Fortymile Gold
I make all of my jewelry with placer gold that I recover myself.
When I started I ran into these same issues. I figured if the
ancient Egyptians could do it, I could too. I learned the art of
smelting gold. Not a simple melt with basic flux, but a smelt with a
flux made with an oxidizer (Potassium Nitrate), silicates and boric
acid. The gold smelts to 22+K. It’s then the most wonderful gold to
work with wether used for rolling or casting. I alloy it then make
my own grain. To me this is what being a goldsmith is all about. My
customers get virgin gold and I call myself Natural Gold
Jewelry…
Hi there,
Thanks for the responses. The material has been tested with fresh
acid and a clean stone at 22k. Attempts at pouring ingots and
rolling the stuff have been a failure. Unfortunately it looks like I
got the brittle variety. On the bright side it makes nice little
granules for my 22k granulation on argentium pieces. The look of 22k
on argentium is reallynice.
I’ll post some photos here eventually.
Thanks again…
Douglas
Great topic. thanks for all the good So funny how the
universe works! I had a letter out to you all ready to send on this
topic just last week! I was beside myself because some reportedly
23k gold from Libya I had melted down was not cooperating - I was SO
looking forward to rolling it out, thinking it would be like
spreading soft butter on warm bread. but it cracked and split ! Even
though I was only rolling it through the mill 3 or 4 passes - I
found out from my friends at Rio that many times brass is used to
solder high karat gold because of the eutectic bond that forms. What
had happened is I had these chunks that would not come up to the
surface during melting - I remelted it several times and eventually I
was able to cut out the chunks as I found them but OMG what hassle
and waste! I now have this beautiful chunk of gold - I have not
rolled it out yet (and I will let you know how it goes) but am hoping
for the best! In my search for a cure for this gold I came across an
Orchid article that states that a *high karat gold could be worked at
a 90% reduction before being annealed again. *What does this mean. I
can stretch it out almost double its size before annealing? ? How
many times are you passing your high k nugget jewelry through the
mill?
Thank you all so much - I just love the collective wisdom that
orchid provides for all!
Blessings
Robyn
Now that is awesome. Where do you live to do this? I can’t imagine
what the cost of access to claims would be these days.
Rick Powell
There is a saying among prospectors. “Iron is the mother of all
gold”. Mostpeople think quartz is the host rock for most gold. But
iron is almost always present in raw gold. That iron is most likely
what is causing your gold to be brittle. Smelting or refining will
make that gold very usable.
Steve
Now that is awesome. Where do you live to do this? I can't imagine
what the cost of access to claims would be these days.
I live right in the middle of the Ca. Motherlode.
Steve
Steve- Can you please provide me some details on your smelting
process? Thank you, Douglas
I was walking past a gun/ammo/hunting store today and there was a
hand-lettered cardboard sign saying “Panning gold tools and supplies
available”, way up in the White Mountains of NH. ?it cracked me up
for we don’t think of NH for panning for gold. ?
Joy
This is taken from “Basement Chemistry for the Prospector” by Dr. A.
K. Williams, Ph. D
Furnace smelting is usually carried out using a crucible made of
graphite (acrystal form of carbon). Of course I don’t have to tell a
basement chemist why we prefer to use graphite, but for any casual
visitor I should explain that at high temperatures the graphite
(carbon) becomes a reducing agent that helps keep gold and platinum
metals in their reduced or metallic forms. Some silica sand or
ground glass is usually added so that there will be aglass matrix
that floats on top of the metal. Some sodium nitrate (Chilean
nitrate or Saltpeter) is added. This nitrate is a rather strong
oxidizing agent. When hot it will oxidize almost any metal, except
for gold and the platinum metals, to its nitrate salt. These salts
combine with the molten sand. Usually some borax is added to thin
the viscous, molten glass.
This mixture is heated until the melt becomes “quiet” with no
bubbles, foam, or lumps in it. The precious metals are now poured
into a mold and the glass or other “gangue” is removed. The black
sand that was in our melt was oxidized to iron nitrate by the sodium
nitrate and is now dissolved in the glassthat we discard. Your gold,
at his point will not be 100% pure. It probablycontains small
amounts of copper, silver, tellurium, etc. The good news is that it
looks like gold and should be of fairly high quality. Plenty good
enough to sell.
I use potassium Nitrate as my oxidizing agent, it does not take very
much, plus Borax Glass from A&B prospecting supply. I also use
standard silica claycrucibles.
Steve
Thanks for the info Steve.
I’ve been in touch with the miner and he says this material is from
fines that have been melted in a silica/clay crucible using
oxy/acetylene and Chapmans flux. I checked out this flux recipe and
it does not contain any nitrates so there probably is some iron
contamination in the material which perhaps along with torch melting
would explain the porous, crumbly texture. I have a small electric
meting furnace with a graphite crucible that I use for casting so I
could resmelt the material under better conditions. Or would it be
better to get some of the fines and smelt them properly myself the
first time? I’m not sure if gasporosity that has been introduced by
torch melting can be removed by resmelting or not.
Thanks again,
Douglas
Yes, there is gold in NH. glaciers scoured a lot of material from
other places and moved it to areas that do not produce gold in situ.
Steve
Douglas
I think re- smelting should take care of your issue. If it does not
work, you are no worse of than you are now…the absolute only
way to know what happens to gold is to do it yourself. Not to
discredit the miner, but You mayhave sponge gold, the result of
removing mercury by using heat instead of nitric acid.
Steve