PonderosaP
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Help to determine what this mineral is
This mineral is really fascinating me because I've never seen anything like it in the ground where I live. The pit from which
I extract it is a long abandoned mining claim. The area of the world in which i live had the richest placer mine in 1900, and some very large gold
fortunes were amassed from what is now downtown.
The mineral is a very dense coarse sand, dark red almost purple in color when first dug up from the mineral seam, which is not very large and
surrounded by iron rich minerals including pyrite, and there are quartz crystals mixed in the formation.
Upon mixing this coarse sand with equal volumes sulphuric drain cleaner (roto rooter 93%, gray and black impurities at the bottom in otherwise clear
liquid) and 12% peroxide a vigorous exothermic reaction occurs, and the silvery metal flakes pictured swirl around. Gas is evolved, with a faintly
"savory" mild smell is produced.
Eventually all that is left after this reaction is washed and filtered are some flakes gold and silver in color, which do not change color upon drying
in air.
Can i have some direction in how to identify this mineral? Are there any easy ways to test quantitatively or qualitatively for things like
arsenic, cadmium, lead, etc?
[Edited on 9-6-2025 by PonderosaP]
[Edited on 9-6-2025 by PonderosaP]
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Deathunter88
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I would guess that's a mix of primarily hematite and quartz. This is what gives gold mine tailings that characteristic red-orange color. This also
matches your observations since hematite dissolves in the sulfuric acid + H2O2 to form iron sulfate, and it is typical of iron dissolution to produce
a "meaty" smell - the same smell that forms when you touch metal coins or blood.
See this example: https://www.researchgate.net/figure/Main-chemical-compositio...
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PonderosaP
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Thanks for sharing your expertise. I'm certain you're correct, it would handily explain the transition from very shiny black-purple (not pictured)
to the rust colored sand pictured above.
The smell of iron is quite distinct, i know it well not only from rockhounding but also metal fabrication.
While the main soluble portion is clearly hematite and [the insoluble one] quartz, i am still concerned working with this mineral.
I would describe the smell as almost like black pepper or onion, evident in the jar pictured after most of the iron has been dissolved and washed
away.
Im left with a hard white flakey mineral with embedded chunks of quartz and flakes of what i hope are precious metals.
I suppose the easy answer is to take serious precaution anyway. I guess i was hoping to be spoonfed some qualitative tests and reagents for
identifying the more toxic elemental friends of Ag and Au.
Yes, I know that i should UTFSE and read a f*cking book.
[While this was a mining claim, i believe the operation began and ended with explosives and a water sluice operation over just one or two seasons
before being abandoned. The site is mostly a pond, teeming with massive frog and insect population. The sample i collected was at the edge of
this pond in the mineral seam. The tailings were discarded at the other end of this pond, acting as a dam for this ~150' long by ~25' wide body of
water. Elsewhere in Montana where cyanide was employed biological life is non-existant. That said, the composition of tailings and the ore itself
is roughly the same. Modern gold mines are profitable at grams/ton scale.]
Edits in []
[Edited on 9-6-2025 by PonderosaP]
[Edited on 9-6-2025 by PonderosaP]
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bnull
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Take a look at Hamilton & Simpson's Quantitative Chemical Analysis (https://archive.org/details/quantitativechem00hami?). Beside being a good book, it has lots of references.
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PonderosaP
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Timely recommendation, thank you sir.
Over the winter i found some discarded equipment and materials from an analytical laboratory, and that is a good companion text.
Are there any good lecture videos available without cost on the subject of analytical technique? (E.G. like M.I.T. had available) Of all the school
classes I've skipped, I regret missing the science ones the most.
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Radiums Lab
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If you are testing for gold then you should add the metal particles to some Aqua Regia and use SnCl2 papers.
If the SnCl2 papers turn black the u might have some precious metals including gold.
Note: This is just a qualitative analysis not a quantative one.
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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Cathoderay
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As far as videos on analytical lab methods you could take a look at the ones by Tyler Johns.
https://www.youtube.com/channel/UCHUQV61jHGEl9ntRR6sQdHw/vid...
"Wet chemistry" unless you happen to have a mass spectrometer in the garage.
More or less it begins with dissolving an unknown metal (if not already in solution) with concentrated nitric acid. (Gold, platinum, quartz, glass,
etc. wouldn't dissolve of course.)
Some tests you can do immediately from that solution, with others you need to eliminate interfering ions first, or change the pH.
If you just want to look for gold there are special tests like melting with a flux in a furnace.
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Sulaiman
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I used this document to prepare for analysis of some lead that I have
I think that it may suit your needs
https://nvlpubs.nist.gov/nistpubs/jres/21/jresv21n1p95_a1b.p...
CAUTION : Hobby Chemist, not Professional or even Amateur
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Cathoderay
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I found a good starting point and overview of qualitative analysis. I bit easier to follow than the Tyler Johns videos.
https://ncert.nic.in/pdf/publication/sciencelaboratorymanual...
Qualitative analysis answers the question "what it is made of?", while Quantitative analysis answers the question " what is it made of and how much of
it is there?". Quantitative requires much more care and measuring the quantities of the test results.
A book about qualitative analysis.
https://books.google.com/books?id=CLxOAQAAMAAJ&printsec=...
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PonderosaP
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Thanks for all the great suggestions. I'm all eyes here
@CathodeRay Tyler Johns looks very helpful, ty. I needed this basic guide, I've synthesized odd amines and ketone but since I had no reference for
smell I wasn't sure I succeeded.
[quote=701183&tid=161108&author=Radiums Lab]If you are testing for gold then you should add the metal particles to some Aqua Regia and use
SnCl2 papers.
If the SnCl2 papers turn black the u might have some precious metals including gold.
Note: This is just a qualitative analysis not a quantative one.[/rquote]
Excuse the phone posting.
Will this work? Bottle says SnCl first ingredient
This is the kind of dirty test I need to actually use my time efficiently.
I can test 200+ prospects all within a 1 hour drive. If I could narrow down to 5 or 6 that probably have 5+ g / ton of material using a rapid
visual test I just might take home a measure able amount of Ag/Au this summer.
[Edited on 12-6-2025 by PonderosaP]
[Edited on 12-6-2025 by PonderosaP]
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Radiums Lab
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https://youtu.be/j3SlZphCjj4?si=GPJ61yHSWcSoSBqu
This clip might help you.
Can you please tell me why you attached the last image.
[Edited on 12-6-2025 by Radiums Lab]
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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Radiums Lab
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And about the solder flux you posted, the liquid is pink in colour
which might confuse you on your final test. Try dissolving some tin in HCl and test it by that way or buy SnCl2 directly as a salt.
[Edited on 12-6-2025 by Radiums Lab]
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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Cathoderay
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I guess I wasn't sure of what you were after. Finding out what the bulk of the sand is would be done with a different approach than looking
specifically for valuable metals.
If you are considering something like gold at a 5gm per ton concentration, that comes out to about 5 parts per million. You would have to process a
kilogram to yield 5 mg of gold assuming 100% recovery.
You might notice in the "sreetips" video that he checks the tin chloride solutions with 1gm per liter standard solutions. Those are 0.1% solutions.
The stain might be easier to see on filter paper, but you are looking for a much smaller gold concentration. The tin chloride test might not be
sensitive enough. If anyone prospected those areas after 1971 when the US ended the gold standard (and the price soared) and it was profitable, they
would have gone for it themselves.
Silver can be detected early in the qualitative series of tests by adding HCl acid so that a precipitate of silver chloride is formed. There are
different schemes used in qualitative analysis, notice that the UNIT-7 scheme doesn't test for silver. Tyler Johns does show that test. Another
difference in the Tyler Johns video is that he uses Thioacetamide to precipitate sulfides instead of the more classic hydrogen sulfide gas. I think
it is pretty obvious that the Tyler Johns videos were made to go along with a textbook. Wet analysis isn't used much in commercial laboratories these
days, it is a tedious procedure. Commercial labs spend the money to get expensive machines like mass spectrometers, X-Ray fluorescence analyzers, etc.
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Radiums Lab
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Yea Cathoderay is right, the SnCl2 might not be very effective at such low concentrations of Au (my bad i didn't notice that you were telling about
the predicted quantities).
Why not send a small sample to an analysis Lab?
You will get qualitative as well as quantitative analysis about the composition of your sand.
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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PonderosaP
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I offer an update, I really appreciate the helpful responses here from @cathoderay and @Radiums Lab specifically, thanks people!
Regardless if anybody is still following I love this forum, it's the last place on the clearweb of its kind.
The screengrab I posted was a lazy way to show I printed that little pamphlet to take into the field.
I had a very bright yellow solution from this ore. When I added the dilute flux I had on hand, I enlisted my wife to witness after showing her
the video from Tyler Johns. The solution I had looked brighter yellow than his! Upon addition of flux we witnessed a significant brown
precipitation develop.
I had documented this with pictures to post, but unfortunately poor judgement led to my phone (and truck RIP little Toyota) being destroyed in an
incredible fireball last week.
On Saturday I brought a newly purchased sluice box to the aforementioned mine site. I don't know if I used it correctly but even if I didn't I
should have exciting concentrates to test! This mine site has been inactive since 1910. I am careful to fill in my hole and hide evidence of
digging with foliage. I'm quite certain there are others looking for gold here.
Thanks for coming to my TED talk SM.
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Radiums Lab
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Yea the brown ppt. is a sign of precious metals, and I think your predictions about the precious metal concentration in the sample is way less than
what actually is present in it . If you have an analysis lab nearby, try to give them a small sample for determination of minerals present in it.
And was the yellow solution formed after addition of aqua regia or just water?
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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Cathoderay
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Well, I wouldn't be so optimistic.
The stannous chloride test depends on the gold being in solution.
You found this sand on (in) the soil by a pond. Any soluble compounds would for the most part have been washed out long ago. There probably is some
microscopic life in the sand with may confuse things.
Also, I think you barked up the wrong tree with that flux. As far as I can find online, K-T Ruby Flux contains zinc (Zn) chloride and muriatic acid
(HCl), no tin (Sn).
In soldering "tinning" means to coat with the solder in a way that forms an alloy with the base metal.
Stannous chloride solution degrades with time. In that "sreetips' video I think he says that he makes a new solution about every four months.
Depending on the situation stannous chloride is used for several other things, in one of the Tyler Johns videos it is used to precipitate a bismuth
compound.
I would look into such things as iron pyrite, "Fool's Gold".
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Sulaiman
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I suggest you use the fire assay method
results easily accepted
if you don't find gold by fire assay then
it will probably not be worth mining/refining the ore
https://en.wikipedia.org/wiki/Metallurgical_assay
CAUTION : Hobby Chemist, not Professional or even Amateur
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Cathoderay
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I've been searching around to find methods.
So here is another idea.
You can get a free download of "Standard Methods of Chemical Analysis" by Wilfred Scott. An old book from 1917 or 1920 depending on the edition.
https://www.google.com/books/edition/_/xJQAAAAAMAAJ?sa=X&...
On pages 192-193, (the pdf pages are higher because thing like the cover and intro are included), the books gives some guideline about testing for
gold. The information isn't very exact about concentrations of the reagents. This method uses solutions of chlorine, bromine or iodine to slowly
dissolve out the gold. I looked up what "purple of Cassius" is and it is the colored substance resulting from gold plus (our old friend) stannous
chloride. "Roasting" is heating while exposed to air, this can do things like convert sulfides to oxides. "Digesting" means dissolve in acid. All this
uses lower temperatures than the fire assay. You would have to acquire several chemicals.
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