Is there an easy way to test if the flecks in this piece of rock are gold? I chipped it from a Rock face whilst hiking in the bush in Corro area a couple of weeks ago, It doesn’t look like Pyrite to me but what would I know lol
Looks like pyrite, but photo’s can be misleading.
Soak it in salty water - if it turns orange you have pyrites.
Thanks I will try that, How long does it take to turn Orange?
I have XRF/XRD machines at my disposal - Message me if you want me to test it for you (Free) - I have the gear, and only too happy to help prospectors stick pins in their maps.
A teaspoon of crushed rock is sufficient (bulk of sample can be the parent rock, with a slight bias to the material you’re interested in) and I’ll send results privately to you with an indication of what you have - If there’s gold, it’ll show.
This offer is open to anyone on here chasing any particular metals/minerals. Only proviso is that it is for personal / Non comm use only.
At least 24 hours.
It does look, promising. Though with rock that hard, you’d need a significant vein for it to be worthwhile extracting. Although the surrounding rock may contain a high percentage of smaller gold particles too.
Lots of Crushing, chemicals, smelting involved. May be more viable to sell as specimens.
Thanks I will see how it goes in salt water for a few days first wouldn’t want to waste anyones time,
Crushing, Chemicals and Smelting… words to be used with Caution around the Corro Ha Haa
Get one of those Quartz Stampers going in the bush, to disturb the Hippies
Make sure you mix some Mercury in with that cyanide too!
And when you retort the mercury, make sure you have a large batch going all at once so if it explodes there will be a big party!
Scratch with a pocket knife…if powdery dust, fragments, chips are dislodged then it is pyrites and if the pocket knife merely grooves it or defaces it without fragments and powder breaking off then it could well be gold.
Gold will scratch in the same manner as lead though lead is softer.
By the way, that quartz is very grey - good sign for Silver oxide/sulphide.
Is it unusually heavy?
Well the salt water made no discernible difference to its appearance, it is unusually heavy I have a larger piece that I thought I would maybe throw in the fire for the night, crush it and pan it? I tried the scratch test but its so fine whatever it is just disappears I am however starting to suspect that its more likely pyrites as you first suspected, the outside of the rock that has been exposed is a rusty colour that penetrates a few mm as can be seen on L/H side of pic
The colour in your photo is not the color of gold but it is the color of pyrites however that might be the quality of the picture.
Can you borrow or locate a stereo microscope…if so look at it under the stereo microscope and give it the scratch test or try to ‘squash’ it. If it does scratch off or break off dust and fragments then its pyrites but if it doesn’t and merely deforms then its gold.
I would not smash it up because if it just happens to be gold then gold in quartz specimens are highly sought after.
I have three quartz/gold specimens and years ago when gold was $300 an ounce the gold value may have been $50 and I turned down offers of $500 each. If you have the real deal then collectors just might go gaagaa over them!
To roast sulfide ores, it takes a good red heat and a good amount of air, but not too hot as you don’t want to melt them. As previously noted, materials that have been crushed to small sizes reacts better with the oxygen in the air. Don’t seal up the material, as it needs to have access to air for the oxygen to react with the sulfur. Even if you get everything right and you’re successful, the stink will probably cause the neighbors to call the police on you!
The unusual things about sulfides is that when heated to high temperatures they will melt. The product of melted sulfides is called a matte, and is highly corrosive liquid. Converting that molten sulfide matte to metal is called smelting. Small scale smelting can be done in a crucible – in fact that is what a fire assay is. When smelting assays are done on high sulfide ores, a couple of iron nails are added to the mix. The metal in the nails reacts with the metals in the sulfides reducing the metals to their metallic state. This is handy when processing silver containing minerals to convert them to silver metal. The addition of scrap iron to smelt mixes is a useful technique to small-scale operators experimenting with smelting techniques on gold-silver ores.
Crush before roasting if you can. Though roasting the entire specimen may help make it brittle and easier to crush.
Keep us updated please, this is very interesting.
See the colour difference between genuine guaranteed gold in this sample and yours - of course the camera can make it look different but gold should be the same colour as the single sample here.
Now in the photo with the three samples the bottom right sample is studded with real gold while the other two have Arsenopyrite, iron pyrite and copper pyrite in them. The gold in the bottom right hand specimen is Golden Progress, Central Otago, NZ but it also has copper pyrites in it at the top left hand side. You can easily see the difference between the gold and the pyrites. If scratched the gold will gouge, and deform but will not break, fracture or fragment, colours, particles or pieces off while all the pyrites will. The pyrites are all yellow or light green and even gray but not ‘that’ gold colour.
OK… in hindsight I should probably have done this first, I took some flakes of gold that I have and compared the colour with the material in the sample photo is very slightly lighter / brassier… I crushed another piece of the rock sieved it through a piece of fly screen and panned it. no visible gold but lots of tiny silver grains, probably cant see them very well in the photo tho.
Yes I can clearly see the difference in the examples you have there, the reason I wasnt sure is because I couldn’t see any flat surfaces or angles on the Gold coloured bits and they didnt glitter when turned to the light, I assumed pyrite would exhibit those qualities, I also wasn’t sure if gold mixed with silver would look different / lighter in colour - I am learning
Do you have any smelting equipment?
It’s very affordable to get some. And you can heat with Butane torch.
I hope you will rescue that Silver!
I dont have any smelting equipment but I do have a Map torch, the rest looks cheap enough so I will invest in some and give it a try, Thanks for the help in identifying my sample and thanks to Lammerlaw for the informative pictures
A couple of questions before I go Smelt my new found Fortunes… I had thought the Coromandel Gold was of a lower purity than the rest of the country in general, being mixed with silver, is it natively mixed with silver? and does the colour vary in nature as a result?
also Pyrite, I have always looked for a crystalline structure to identify it as well as its weight and physical attributes but I couldn’t see any obvious crystalline structure to the sample I had using a Loupe, I guess if I had used a Stereo microscope it would have been clear?
Pyrite need not be angular. Copper pyrites is not angular and iron pyrites will form cubes but also does not necessarily always be cubic.
Another test is to hit a piece with a hammer or grind it on the matrix…if it shatters and breaks then it is pyrite but if it just flattens or distorts then its gold.
Gold with silver in can be a little lighter in color.