A very colorful Stannous Chloride reaction.

[misterstink]

Second edit: I just realized that there is an entire forum dedicated to sampling/assaying/testing - Please let me know if this belongs there more than here.

I was testing a mixture of unusually heavy cons in my pan along with a few larger pieces (about 1/3rd the diameter of a copperhead BB). Dissolved it in aqua regia, and the attached = the results roughly a minute after applying about three week old Stannous chloride.

This is a very colorful combination. Fairly certain it tests positive for gold and palladium. Just hoping for some more experienced opinions.

Thanks.

Edit: Adding another picture, from the same ore, treated in the same manner. Was wondering about that somewhat orange/rust/yellow-brown color could be platinum? This photo was taken maybe 30 seconds after.

 

[nickvc]

Solutions of mixed elements can give a range of colors when tested so to test you need to precipitate your gold and then retest, another alternative is to take a small sample on a plastic spoon add a little copperas to precipitate the gold and then test.

 

[misterstink]

The precipitate was in suspension when I emptied it onto the paper towel. I used about a 2/3rds aqua regia and 1/3rd ore in a 5ml (guesstimate) solution. I also used a piece of gold leaf in the same measurements, and the results were exactly as I've read. Applying the stannous chloride to the gold mixture produced the proper reaction in the spoon test (black) and the same on paper towel; with the exception of paper towel colors changing over time.

These results were treated the same as the gold leaf and the pictures are the result. Initially, on paper towel and q-tips I only had a light purple show up. Letting it sit for 24 hours resulted in this confused rainbow mixture.

Edit: Or were you telling me to precipitate the the supernate? Which I think I kind of did in this instance. Sorry, I am very tired.

 

[nickvc]

I keep it simple as it’s easy for everyone to follow so what I’m saying is yes the stannous will remove the gold from your sample if enough is used, that is what the black purple color is, but to test your solution for any other values you need to precipitate the gold , do no black purple color, and then test the gold free solution, to achieve this you need to use specific selective reactants that only precipitate gold leaving the other values in solution.
As I said the other colors you are seeing is the mix of all the other elements in solution.
Lazersteve I believe did a fantastic post about testing a mixed solution many years back and perfectly describes how to test for each value in sequence, use the search function it’s on the forum somewhere.

 

[misterstink]

Alright. I will look for that post.

Thank you.

 

[Lino1406]

Multi-colored results are typical for palladium. Brown, red, green, blue and violet. Preceding end line which is black
From: "Explaining the use of stannous chloride." (Available at Goldn'scrap)

 

[misterstink]

Is there a way to precipitate everything out and test for just Platinum? I've been searching and not finding.

 

[FrugalRefiner]

The classic test described by Harold_V is to drop the gold out with ferrous sulfate (copperas), then drop the palladium with DMG, and final test for platinum with stannous. You should be able to find his description using a search with a few of those terms and author as Harold_v.

Dave

 

[Platdigger]

I may as well join the crowd. There is also this for pt:
TEST NO. 45: Platinum - Pt.
NOTE: See "Second Procedure" Part Two regarding platinum.
1. Place particle, or concentrates size of pea in test tube.
2. Add 1 cc nitric and 3 cc hydrochloric acid, (aqua regia).
3. Boil over lamp flame 5 minutes or more, then let settle.
4. Place about 25 drops solution in clean evaporating dish.
5. Boil over lamp flame to dry, then just a little longer.
6. Let dish cool, then add 3 cc water; reheat to boiling.
7. Filter solution into another clean evaporating dish.
8. Add potassium iodide equal to about 1 grain rice, or less.
RESULTS: If platinum present, a rose-coloured solution, at once or after dish had set for 30 minutes or more.
NOTE: Sulphides may give red color; proceed as follows:
9. Let dish set until dry; add 2 or 3 more drops of plain water
RESULTS: A rose-color if Pt.; no red or rose if sulphides.

These tests are found here: "Quick Qualitative Testing of Rocks and Ore"
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=44&t=10932&p=194194&hilit=quick+metal#p194194

 

[Lino1406]

Always have a saturated NH4Cl solution. Precipitation of a double salt of ammonium-platinum chloride is good enough for me

 

[misterstink]

Thank you all for your help. I'll order those chemicals and test those methods. I can't core drill or anything like that for the time being. And I enjoy doing the assaying myself so there are going to be plenty more rocks to study and test. It looks like this website will be invaluable given my lack of experience in this area. Again, thank you all for your help.