Identification please

[Driscom]

Any ideas on what this might be? Found with a detector in a known gold area. It was about 3 inches in the ground near the top of a large pile of dirt dug from a shaft. I polished the end with a soft buff on a grinder. The original colour was similar to the surrounding ground it was found in and only turned green when I soaked it in vinegar to get the 'soil' off. About 35 long and 30 wide - and weighs in at 52 grams. Showed a pic to a geologist, who wasn't sure, and to an experienced 'detectorist' who suggested it was slag from a ingot pour.

Any ideas appreciated.

 

[Nightjar]

Possibly bronze? Mystery though, why it was where you found it?

 

[Driscom]

Thanks, my thoughts as well. Not worried if its valuable or not - just pondering the history

 

[grubstake]

The problem with IDing this specimen from a photo, is that both of the treatments you've applied to it have dramatically changed its appearance. Unfortunately, you've muddied the waters, so to speak. :8

Considering its location further, the material at the top of the heap is the last stuff dug from the excavation phase of the shaft, so the closest to the paydirt layer, if there was one at the bottom. It's also where dropped material from miners climbing up out of the shaft would land. On this basis, I'd speculate that it's perhaps a natural nugget of alloyed gold. ie. electrum (https://en.wikipedia.org/wiki/Electrum). The history of the goldfield may provide more info about the purity of finds in the area to support this theory.

If you can locate somebody with an XRF gun, they'll be able to instantly tell you whether or not there's gold in it - try pawnshops and jewellers for access to this technology.

 

[Driscom]

Nothing like being a newbie and 'muddying' the waters - LOL. I have a pic on my phone with it in its original condition, will try and upload. Might try the local pawn shop for an XRF. Will do more research re electrum and the area - thanks for all the info.

 

[Driscom]

This was before I decided to play chemist )

I just gave the side a light buff to see what was underneath

 

[markie_d]

Any ideas on what this might be? Found with a detector in a known gold area. It was about 3 inches in the ground near the top of a large pile of dirt dug from a shaft. I polished the end with a soft buff on a grinder. The original colour was similar to the surrounding ground it was found in and only turned green when I soaked it in vinegar to get the 'soil' off. About 35 long and 30 wide - and weighs in at 52 grams. Showed a pic to a geologist, who wasn't sure, and to an experienced 'detectorist' who suggested it was slag from a ingot pour.

Any ideas appreciated.

https://www.prospectingaustralia.com/forum/img/member-images/19303/1603924299_p1020342.jpg

Some alloys can also melt during bad fires, i have seen melted metal around burnt out cars i have stumbled across in the creswick forest.

Bronze and brass both melt at below 1000c so technically a hot camp fire could almost melt them.

 

[Rockhunter62]

Definitely copper based.

Cheers

Doug

 

[grubstake]

The part you buffed will be perfect for XRF testing, so that's a plus.

The appearance of nuggets as found can vary quite dramatically between goldfields. I was an experienced prospector by October 1984, when on a day trip to Kingower the only piece I ever found there came out of the ground. It was the size and shape of something you'd find on a cheese board and looked like tarnished brass. Since it was shallow, easily detected and looked like a piece sliced off something, I pocketed it assuming it was just a lump of scrap metal, until we got back to the car, cleaned it with water and a toothbrush and started to consider its obvious weight. Back home, a day or two in hydrochloric acid confirmed it as a flat, solid 37 gram nugget!

 

[Big Johno]

I too have found an identical piece of ???? in WA near Leonora and mine was bronze, and I presumed it was from an old campfire as there was a charcoal patch around it.
Thought I had joined the 1 oz club until I got back to the camp and checked it out.

 

[Deepseeker]

Bit of a long-shot, but there was a practice sometimes in the past of making "Spurious Gold" to gain financial advantage.

John Tully and Ruth Moore published a book in 2000 called "A Difficult Case" about a Chinese miner in Victoria in the 1860's by the name of Jong Ah Siug, who at one time was charged with making Spurious Gold.

An excerpt from the facts surrounding the case follows- Jong Ah Siug was born in Zhongshan, in southern China. Arriving in 1855, he moved around the diggings of Western Victoria for a time before settling in Bealiba (north of Maryborough).

Jong first made himself known to the authorities after attempting to sell spurious gold in 1863. Making spurious gold involved mixing another metal - usually copper - with gold to produce an alloy that resembled pure gold. In response, shopkeepers had begun to use a flame test before they purchased gold. If the flame burned green, it showed there was copper mixed into the gold.

-Just a thought!

-D.S

 

[user 4386]

If I knew the location I might be able to tell you. Unfortunately you probably cannot PM yet, but there is no obvious reason why I would thinkm you would want to keep it secret. Just the nearest town would possibly do.....
How hard is it on Moh's scale? Copper is 3, bronze is 6 (you cannot scratch bronze with a "gold" coin). What colour is the powder when you scratch it?
It definitely contains copper.

 

[Muk]

Stick it in some alibrite if its gold it wont damage it only clean it up cheers Muk.

 

[Driscom]

Thanks all,

I think Goldierocks, Nightjar and others might be on the mark with the bronze like ID. I did the coin test and the nugget is quite hard. I'll wait and take it to Canberra next time I go that way and see if I can find a XRF gun just to make sure there is no gold in it.

Thanks Deepseeker for the 'spurious' gold story - could well be one of those. There were Chinese miners in the area, who knows???

 

[Moneybox]

My nephew lives at Cloncurry and works deep underground in a copper mine. He gave us some native copper that is formed just like gold in nuggets, many weighing better than an ounce. The copper does have a more pinkish colour but so does some gold. The green certainly indicates a high copper content but an interesting find anyway. I think Driscom's suggestion for a zap with the XRF gun is a good idea.

 

[davent]

Just following this one up, was it ever identified?

 

[grubstake]

If it ever was, sadly Driscom didn't come back to tell us.

 

[Hawkear]

Specific gravity measurement and hardness estimate would be the first things to check. Also if the clean metal tarnishes with acid.

 

[user 4386]

I don't think I suggested bronze - my guess is native copper but hardness alone would be fairly diagnostic, combined with the colour change. Native copper does not react with common acids at room temperature but does react slightly with acetic acid (vinegar):...



I suspect the actual reaction of the surface layer formed is with oxygen from the air to form green brochantite (a hydrous sulphate) - there is often sulphate ion around ore deposits - or with carbon dioxide from the air or soil, to give things like malachite (copper carbonate).