The smallest visible gold particle

What is the size of the smallest visible gold particle?

Does anyone know? I did a little research on it and found that sells gold powder SG 19.3 (as
well as gold oxide powder and gold acetate powder). They say the size
is as low as -325 mesh which is about as fine as silt. -325 means the
size is 44 microns or smaller and a micron is 1/1,000,000 mm.

A practical application might be in ceramics if you wanted to
sprinkle gold dust on your glaze. What size would you order from
American Elements?

Theodore Gray writes in “The Elements” (page 182) that gold leaf is
500 atoms thick and is picked up with a hair brush made of red
squirrel hair (he does not say what to do if there are no red
squirrels around).

a micron is 1/1,000,000 mm 

No, a micron is one millionth of a meter,.001 mm. Note that the term
was officially revoked by the International SYstem of Units people
in favor of micrometre, but everyone still uses it.

Al Balmer

colloidal gold particles are used in immunochemistry and as
markers/enhancers in tissue pathology. these gold particles are
typically 20 nanometresa cross but can go down to 3nm. Particles
smaller than this are used for calibration of Transmission Electrom
Microscopes but more usually microparticles with a distinctive
lattice structure or plane are used and this allows you to determine
resolutions of 1.02nm (1 of 3 gold lattice planes) or smaller. Gold
particles in ceramic glazes are about 2 micrometres across. A
nanometre is 1/1000 000 000 of a metre. the equivalent resolution
for the human eye would be seeing New York from space and it
appearing to be the size of a pin head but being able to discern a
grain of sand on the street. The Hubble telescope has a resolving
power of approximately 1/1000th of this. That is the trouble with
light, wave length too big. Nick Royall

Right you are, thank you. A micron is a billionth of a meter.

Please have a look at webelements and the Au lattice. I find it
confusing. The 3D drawing is supposed to show the smallest Au crystal
which I thought was cubic and thus 8 atoms. But they show a
rectangular box and >8 atoms. This might be the size one would want
to sprinkle on ceramic glazes.

As I understand the latest research on the gold bug “Delftia” it
takes single Au+ ions and uses them in its metabolism. But they are
toxic so one must wonder about the astonishing 100 ppb reported in
human body v 3 ppb in Earth crust. If we are taking in a lot of Au
ions that may not be healthy. Could the skin even absorb gold from a
ring? I know I am a little bit allergic to some kinds of metal rings.


No, a micron or micrometre is a millionth of a metre, the nanometre
is a billionth of a metre. Everything is toxic if exposed to the
wrong amount, excessive oxygen causes your cells to explode but when
are you going toexpose your internal organs to pure oxygen"There are
plants thatabsorb heavy metals as salts and excrete them as metals.
Lichens and the Alpine Catchfly (variscia alpina) being the most well
known of these, miners in Norway used to call them “kisplant”.Look up
the work of O W Purvis of the Natural History Museum, London for more
details. Nick Royall

Everything is toxic if exposed to the wrong amount" says Nick.
Agreed. Selenium is from a word which has to do with "lunar"

Selenium is sold across the counter in drug stores but too much of
it makes one “luny” so farmers keep their stock away from loco weed
which concentrates Se.

But what puzzles me is the high 100 ppb of Au in the human body as
we read at Web Elements when silver and PGE are not mentioned at all
(BTW how many atoms would you say that is and what is their form -
ions? colloids?) Could some of it come from the fact that we live in
proximity to gold with all our jewelry, kitchenware, dental work etc?
The skin is absorbent so when I react adversely to metal rings I
think the skin is giving me a signal that it does not want these
metals in the body.

The only two plants I know of which concentrate gold are mustard and
eucalyptus. I have not eaten many eucalyptus leaves or koala bears
recently so how does Au get into the food chain? It is a mystery to

If we are taking in a lot of Au ions that may not be healthy. 

100 ppb of anything is far from astonishing. I wouldn’t worry - the
LD50 for gold is greater than 1.4 g/kg, or a bit over 3 troy ounces
for a 150 pound man. (Enough to be worth recovering if you die of
gold poisoning, your heirs should send you to the refinery.)

Al Balmer

100 ppb of anything is far from astonishing. I wouldn't worry -
the LD50 for gold is greater than 1.4 g/kg, or a bit over 3 troy
ounces for a 150 pound man. (Enough to be worth recovering if you
die of gold poisoning, your heirs should send you to the refinery.)

Thanks for the laugh, Al. I will change my Will right away and since
I have a backyard kiln my heirs will be able to extract the gold from
my urn easily.Come to think of it, even at 100 ppb that is a
pinhead-sized quantity which is quite visible and could be set inside
a plastic bead. OK, I’ve seen too many GE “Imagination at Work” tv

But here is a more serious question. If you refer to the Journal of
Nanoparticle Research, Augus 2011 you will see an article on diatom
extraction of gold by Shrofel et al. The Au was found right in the
silica cell walls. The 100,000 species are ubiquitous. They may be in
your garden and even your basement if it is damp, feeding away on
silicic acid to build their shells and should that acid contain Au
ions, Shrofel et al proved that at least two species would ingest it.

Could diatoms be the means by which Au enters the food chain to

It comes mainly from your diet but also from the dust you breathe in
etc. As for extraction of au from human bodies, we excrete it via
our toenails (2g/t) so no need to murder and incinerate your entire
family, just keep their toenail clippings. Fingernails dont cut the
mustardthough. Nick Royall

Thank you Nick. You say not to do in the relatives - just keep their
toenail clippings. Cousin Orville has an auriferous look about him so
I was going to start my advanced research with him. I think you have
saved his life! Silica is an essential for human health but where
does it show up in the body? Maybe the harder tissue like toe nails,
teeth and bone.

There is such a strong affinity between silica and gold in magmas
and in hot, acidified water (which leads to hydrothermal and
epithermal ore bodies) that I would look for gold in the human body
wherever there is silica. At McLaughlin gold mine in CA the gold is
found in opal which is hydrous silica. What do shellfish do with the
gold they take in from sea water? Do they deposit it with the calcium
carbonate in their shells? To get the varied colours in mother of
pearl would require a variety of chemicals would it not?

Gold is not stored in the body hence the excretion via the toenails.
The association between gold and silica is not an affinity but a
circumstance. You need very specific temperatures and pressure for
gold deposition inhydrothermal orebodies and these are slightly
different from the conditions that gold is deposited in massive
suplhide orebodies. Gold is basically one of a number of elements
that can really be considered as dross when it comes to rock forming
but we like it and so nature has made it relatively asy to find it in
one type of deposit. The colouration in pearls and mother of pearl
shell is down to the organic layers between the calcite/aragonite
layers rather than being mineral based. The layersing give the shell
its strength, which on a size for size basis is tougherthan rolled
armour plate. This organic material is often highly toxic so that is
wy you should be VERY careful to avoid breathing in the dust when
cutting and polishing abalone and MoP. Nick royall

I thought you were pulling my leg, Nick - toes and all. I could not
find a source online for toe and I assume finger nails excreting gold
or any other toxin.

Still we have the problem of where it comes from if not jewelry and
what the normal-healthy ppb is. So I look to the food chain. Thanks
for the warning on abalone powder as toxic. When I send my assays in
this spring I will send in some nice, shiny clam shells, powdered up.
I got these from mucks where I have good reason to think there is a
nearby gold deposit. I will post the assay to Orchid, probably

BTW I did two crazier assays than that - both in epithermal
locations. One was a kind of bluish-green powder in the rocks that
looked organic to me. The other was glossy slickening on rocks which
is usually chalked up to polishing caused by fault movement. I had
just taken my first kiln-ceramics course and it looked like glaze to
me. Both samples gave astonishing gold values.

PS - Cousin Orville is still alive and well.

Gold is not stored in the body hence the excretion via the

I’d like to see references for that. The only reference I can find
indicates that gold nanoparticles of a particular size range may be
deposited in the liver. Other particles whih get to the lungs stay
there. The only references I can find to nails are the usual rumors
with everybody giving uninformed opinions, both pro and con, on sites
like justanswer and yahoo.

Al Balmer

The only references I can find to nails are the usual rumors with
everybody giving uninformed opinions, both pro and con, on sites
like justanswer and yahoo. 

Toenails are not a significant part of the gold excretion process
according to these two studies:

The first, a study of metabolism of gold used in rheumatoid
arthritis treatments showed, “…70% is recovered in the urine.
Highest gold concentrations are found in the reticuloendothelial
system, adrenal glands and kidneys, while the bone marrow, liver,
skin and bone contain the greatest quantities of gold.” Metabolism
and distribution of gold compounds. Gottlieb, NL., J Rheumatol
Suppl. 1979;52-6.

The second more recent study says: "When gold is given orally, 85UKP
95% is excreted in feces and the remaining 5UKP 15% in urine,
regardless of dose. The majority of gold recovered in the feces
represents nonabsorbed gold, gold breakdown products, gold shed from
mucosal cells to which it was adsorbed and a minor contribution from
the biliary tract."Gold Nanoparticles: A Revival in Precious Metal
Administration to Patients; A. S. Thakor, J. Jokerst, C. Zavaleta,
T. F. Massoud, and S. S. Gambhir. pubs.; 2011.

Reading other articles, it seems the quantities excreted and
retained seem to be related to the size of the particles and manner
of delivery.

Carol J. Bova

The toenail gold was from a study done 35+ years ago so reliability
is something I havent looked into. Peters shiny rocks are called
slickensides and are indeed a result of fault movement. If you rub
your finger along them you will notice a rough and a smooth direction
and that tells youwhich way the rocks have moved relative to each
other. Ancient (relative to rock age) faults are indeed often good
sources for disseminated gold as they have a massive pressure drop
compared to the unfractured rock so the gold migrates there. Many of
the gold mines of Wales of the late 19th and early 20th century ere
bonanza type mines based around high levels of gold in faulted rock
that had later hydrothermal quartz veining. Nick Royall

Thank you for a nice piece of research Carol. This is way beyond my
chemistry background and it takes us into a number of disciplines
from nanoscience to pharmacology. Would everyone agree that the 200
ppb gold in humans is either food chain in source or jewelry? Air
seems unlikely.

And also that it is not necesarily healthy so we do not really know
the good health norm?

I would say your comment about particle size is important - small
enough and it will likely be lodged in tissue. Question then is - how
small and ionic or non-ionic. Microgold according to web elements is
found in sea water and stream water too. In what form? Ionic or
cubic-lattice crystals? Can gold actually be ionic in water or does
that require acid, chlorine etc?

Lots of questions for lots of research…

I remember ingesting ‘Montana Gold’ Schnapps maybe 25 years ago.
Small particles of 24k gold leaf was suspended in the Schnapps! At
the moment I am getting prepared to melt down a bit of flour gold
which I recovered from ground ore. Some of this gold is so fine you
can’t even see it unless it is in a pile. Always a pain to deal with!

I’ll drink to that!

I was looking at a couple of one ounce gold wafers here and I
thought, well a one gram piece is about the size of a small pea and
and one mg would be a thin and small pinhead. So I would guess that
your smallest visible flour gold units are much smaller than that.
Maybe 1/10 mg. And still thousands of atoms - maybe millions.

Why is all this important? For reasons of absorption and nutrition
as we have been discussing - and then the source. Absorption through
the skin from jewelry or food chain?

Also, practical prospecting and gold deposit formations. Microgold
goes down into acidified boiling waters just 4 km deep or less. I
suspect that is all non-ionic in cubic lattices as it goes down. Nick
probably knows more about this. It could also accumulate as a lode if
there are gold traps just as river gold traps accumulate placer gold.

Then I think the Au+ ions under pressure would be squeezed back up
toward the surface by pressure and they would precipitate out as
cubic gold again in the cooler fractures and in pores of porous rock.
So you would get the porphyry lodes and other deposits. I am going to
guess that in the temperate regions there are gold bugs, many species
of which are as yet undiscovered. I think that bluish-green material
I found in an epithermal location with all the gold in it may have
been biological in origin.

Bottom line? If a species of microbe is discovered in the temperate
regions say 1-2 km down, and it ingests either micro-gold in lattices
or Au+ ions, that could lead to a new method for milling micro-gold.
The bugs may well prefer the Shnapps form for feeding. Gotta keep
your workers happy!

The current Smithsonian magazine contains an interesting article
discussing the use of gold nanoparticles in treating cancer.

Another article deals with eucalyptus trees. Their deep root systems
take up water from depths of 130 ft. If that water carries
microscopic gold, the metal would deposit in leaves and branches.
Should gold be revealed through analysis of these tree bits,
geologists would have another clue for prospecting deep underground.

Smithsonian magazine is mind candy of many flavors.

Judy in Kansas, where yesterday temps were in the 60s and plummeted
to the teens within the space of a few hours. Deep freeze time

The current Smithsonian magazine contains an interesting article
discussing the use of gold nanoparticles in treating cancer. 

Thanks for the article from Smithsonian. The Dutch researchers are
attaching gold to cancer cells and when it is zapped with the right
wave length, there is a rise of up to 100 degrees in temperature.
Also gold has been used in arthritis treatment since 1935 but
wiki/Gold_salts says the ionic compounds of gold are used less now
because of side effects. The gold can be taken orally which may link
to food chain source but the 200 ppb in human body is still a big
mystery and as you say eucalyptus trees take gold in but most people
do not eat a lot of eucalyptus leaves or koala bears.