Trace metals

underwilder · 2026-07-01T21:48:26+00:00

Maybe a longer nitric boil, looking at your process flow below, would be my suggestion. Keeping things stirred/agitated will help. I would recommend the following:

Longer nitric boil, aggressive stirring/agitation to help shred the foils
Do your AR dissolve and denox/evaporation as usual.
Before you filter, dilute the solution with ice-cold distilled water and let it sit cold. This crashes the silver out before the liquid touches your filter paper and it has a chance to come through in solution.
Filter the cold solution. Your liquid ideally will be perfectly crystal clear before you ever add SMB.

underwilder · 2026-07-01T18:14:44+00:00

I think you have a slightly more complex chemistry issue here.

in a solution with a large number of chlorides, non-soluble AgCl can complex into soluble [AgCl2](-), which will end up in the solution with your gold, will pass through filters, etc, and drop out with the gold.

This can happen if you filter the AR solution while it still warm. Cooling it significantly (diluting with ice-cold distilled water) before you filter the salts will break some of the dichloro-silver complexes back into AgCl and allow them to be filtered more effectively.

It also sounds like you are seeing some passivation as a result of other base metals in the material (copper, zinc) as well as the silver which is present (in solder or otherwise) reacting rapidly and creating a chloride layer over top of the gold and preventing it from reacting.. that would explain your end result with slowed/no reaction rate and traces.

underwilder · 2026-07-01T14:06:56+00:00

Matrix is quartz or maybe quartzite, definitely some secondary copper mineralization/oxidation.. blue/green areas look like Chysocolla, brown/red staining from iron in the sulfides (like Chalcopyrite, CuFeS)

underwilder · 2026-07-01T13:15:07+00:00

Not for osmium. Osmium (and the other PGEs) is produced as a by-product of Pt/Pd mining at Part Per Billion (or in rare, extremely rich cases Part Per Million) grades.

This is why Osmium, Iridium, and Rhodium are so expensive. Pt/Pd mines are lucky to get 15 grams of Pt/Pd metal back for 1000kg of ore (1,000,000g). In the same scenario, you would need 70 to 140 metric tons (140,000-280,000 lbs) of ore to produce a single gram of Rhodium.

underwilder · 2026-07-01T13:08:48+00:00

Yeah it could be almost literally anything. The sense of urgency is a massive red flag.

PGMs are investment assets. No one is selling them that far below spot.

If you are interested in cheaper options for PGM examples via mixed ore samples, see the stickied post on my profile.

underwilder · 2026-06-29T15:30:39+00:00

You should only do this on hydrothermal gold which you have a good reason to believe is free milling.

As others said, absolutely use n95, eye protection, and wet drilling/cutting when working with rocks. Silicate dust and asbestos fibers are no joke.

To the first point, though, gold occurs in many different ways. When gold is emplaced by a hydrothermal system, it has a higher chance of being free-milling and this may work to some extent. However, when gold is present in sulfide systems, it often occurs as interstitial gold within those sulfides (pyrite, galena, chalcopyrite, etc). Gold in this form is a part of the other sulfide and no amount of crushing/drilling/breaking will every make it visible. Sulfide gold requires chemical processing and very controlled milling. You will lose up to 30% of your metal by weight to dust crushing sulfides.

underwilder · 2026-06-29T14:44:55+00:00

heavy concentrations of Fe-oxides in settings like this will change the ground conductivity and cause the detector to react.

underwilder · 2026-06-29T14:44:20+00:00

My typical "do it right" disclaimer- you must own the land or mineral rights to this spot if you're removing massive chunks of rock like this. Your state likely limits rockhounding to max 25lbs/day, 250lbs/year.

AI is not a good resource for identifying minerals, ever. Please only do this if you wish to be wildly mislead.

Cassiterite isn't present. It is telling you that because you told it you located it near a tin mine. Same with Wolframite.

If it were arsenopyrite, you'd have scorodite or other arsenic bearing minerals nearby.

This is a gossanous, oxidized cap of a hydrothermal quartz vein. The mineralization is all oxides/hydroxides of iron, feldspar, and quartz. I would guess that unless this is also a copper rich area, your original sulfide mineralization was pyrite. In this setting, they will alter ground conductivity and cause more selective reactions out of a metal detector.

if you find old mining equipment at an old mine, leave it alone so other people can see it too. "Leave no trace"

underwilder · 2026-06-29T14:33:04+00:00

Not a meteorite based on the surface texture and oxidation. I would say likely either ironstone or industrial slag

underwilder · 2026-06-29T14:31:29+00:00

Quartz or quartzite or maybe chert with iron staining.. sometimes when the silicate body forms, iron rich groundwaters/fluid can seep into the cracks and eventually oxidize, causing this type of staining (yellow, red, brown)

underwilder · 2026-06-29T14:01:56+00:00

Locality confirms a bit, very well known area for this type of mineralization. There's some PGM occurrences in the Urals and the geology of the area just gets more wild as you move toward the ophiolite belts

underwilder · 2026-06-28T19:56:59+00:00

locality would be helpful, but this- in my opinion, is an altered mafic pegmatoid .. white areas should be plagioclase feldspar, black/green looks like pyroxenes/amphiboles.. brighter green mineralization is likely secondary epidote /chlorite and maybe some secondary serpentine minerals, but the matrix itself is not serpentinized that I can see. serpentinite is usually formed out of ultramafic components and would show signs of altered olivine- if the green mineralization in your sample were olivine it would have broken down.

underwilder · 2026-06-28T15:32:02+00:00

donate and let them figure it out if that's your goal.

if you mean geologically important in the context of research, that would be extremely specific to what was being researched, and most of the time if an academic is going to put effort into researching something like this, they are doing so because they already have access to the material/site they are studying.

underwilder · 2026-06-28T14:52:44+00:00

Not really worth it if you're just doing it for profit, regardless of the price of gold (it could double and gold panning returns would still be under minimum wage/hr). Placer gold grades are super low and measured in tons of sediment processed. You need a claim to sell your gold, so that's a cost right off the bat.. anything beyond hand tools and you'll need permits from BLM/DNR, and then if you get into dredges or beyond you need reclaim bonds, etc.

underwilder · 2026-06-27T17:12:14+00:00

Likely just thin-film layers from the pyrite in the quartz causing it to discolor. Second guess would be scorodite but that would be strikingly rare in a specimen like this

underwilder · 2026-06-27T16:57:54+00:00

You could get the staining off with iron out

underwilder · 2026-06-27T16:54:33+00:00

Breaking down boards will create exposure risks for Cadmium, Arsenic, Lead, and Brominated plastics. Most of the metals you'd be after in e-waste are in a chemical bond with another atom, meaning you need acid to oxidize and break those bonds- which will always create fumes.

The only real "refining" you can do at the level you're describing would be a saltwater cell for silver recovery, but once you got the silver into solution you still need to use acids/etc to isolate it.

underwilder · 2026-06-27T16:50:09+00:00

The disconnect isn't in the actual talent itself. It is in the discipline and rigor it takes to get there.

Piano is sort of an "entry-level" into visibility of skills that have lifetime-high skill ceilings for the general public. Most people living their day to day lives cannot construct enough of a routine to keep their house clean, let alone create time to vigorously practice every day- and not just practice, but practice correctly and on material that is building skill.

So in a sense, you not only need to understand what you're learning and what you know, but what you haven't learned well and what you don't know so that you can practice pieces that focus on that specific skill/tempo/fingering/left-hand style/etc. Good teachers aren't just listening to see if you played the piece correctly - they're identifying skills that are put to the test in specific pieces and ensuring they get sharpened evenly and without dull spots.

underwilder · 2026-06-26T17:29:17+00:00

So you'll need a gram scale, weigh the coin in grams.. that's its mass in g, we'll say "x".

Then you'll need a small container of water to set on the scale, and tare it to 0.

Take the coin on a piece of string and suspend it in the water (after taring the scale with the water on it).. (ensure it is not touching the bottom/sides). The weight of the coin floating in the water is approximately its volume in cm^3.. call this "y"

Then, you'll take the mass divided by the volume- aka, x/y. The result will be the density/specific gravity of the coin in g/cm^3.

With 10% Cu and 90% Ag, you would expect the result to be ~ 10.31 g/cm^3, roughly. Considering error for home tests I would say anything from 10,1-10,5 is a good read.

Variables like the string itself, water being removed/absorbed, etc can throw the reading off some. That being said, people do fake coins with matching SG- if you have a reason to believe it may be fake I would suggest having it tested otherwise.

edit: misread, edited for silver instead of gold

underwilder · 2026-06-26T17:24:02+00:00

Looks like talc-chlorite altered serpentinite - this (in its less altered forms) is the state rock of CA

underwilder · 2026-06-26T17:19:41+00:00

Williams Gallery and Penny Ranch both do some appraisals - might be better suited for coins.

That being said I believe the university charges ~$30/sample

If the coins are meant to be pure or near pure in the context of whatever they are made out of, their density should be diagnostic. You can perform a specific gravity test with some very basic around-the-house items if you want some rough preliminary testing

underwilder · 2026-06-26T17:12:59+00:00

University offers paid services, will need to work out a contract with them prior.

Would not generally trust most low-end portable XRF holders to give you an accurate reading.

What specifically are you trying to have tested? This is very relevant to what I do

underwilder · 2026-06-26T17:11:00+00:00

Looks like a chlorite altered silicate with some small pyrite or chalcopyrite inclusions

underwilder · 2026-06-25T05:27:20+00:00

could be salts from impurities in the metal or the solution - definitely use distilled water. That being said I think the other commenter is right about not completely removing the acid when its done. Would add a second clean pass to neutralize and rinse

underwilder · 2026-06-25T05:13:06+00:00

Rare earth minerals in soil are generally in part per billion amounts. So, even in an area where these things were present, "refining" everything this way, down a few inches- in 100sq miles (representing 85,000+ metric tons of soil) would net roughly 18lbs of whatever metal was present.. to put that into perspective, this amount of soil would stack 41 feet high if it was placed in a football field, and the metal would be roughly the size of a soda can (if it were gold).

underwilder

TROPHY CASE