A nice day in May.

Hi everyone.

Our group enjoyed another beautiful day out at Castlemaine yesterday. Only a few nuggets were found with Moredeep snaffling a nice little 1.6 gram piece.

I managed to locate 2 small ones in a different area to where I usually detect.

The first one weighed in at 0.18 gram and the larger piece at 0.32 gram. Half a gram all up.


I also found this strange piece of metal. This is the 5th piece like this, the first one I found in 2014 which I took in to get checked when I took a nugget in to get XRF scanned. I was told that piece had about 8% gold in it.


I originally thought it was copper and dipped it in acid and then scrubbed it with steel wool. It cleaned up a bit and gave off a bit of residue whilst scouring with the steel wool. If anyone can help with it’s identification that would be great.

Regards Axtyr.

Could it be a lump of mercury amalgam?

Nice going, well done Axtyr.
If your silver looking slug, is found to be non magnetic, then it may well be a piece of natural silver ore, or piece of melted down silver ore, mixed together with a small percentage of gold within.
If your silver looking lump shows magnetic characteristics (high in iron oxides), then it may well be a piece of galena, or that of a manganese ore (with pure manganese ore by itself being non magnetic), containing a small percentage of gold mixed within.
For it to be a solid lump of mercury amalgam, it would have to be very low in actual pure liquid mercury content, with a much higher amount of other alloys combined within (such that of copper, tin, or silver).
Pure liquid mercury, were used back then by the old timers, in order to separate/extract fine gold from poor grade ore, by crushing the ore to almost a powder, mixing it with liquid mercury, then boiling off the mercury to a vapour, leaving behind mostly gold.
This type of process of gold extraction, is not recommended in todays times for use by the average hobbyist detectorist/gold prospector, because of the dangers involved by mercury vapor inhalation poisoning. 

Kon

Kon61gold wrote:For it to be a solid lump of mercury amalgam, it would have to be very low in actual pure liquid mercury content, with a much higher amount of other alloys combined within (such that of copper, tin, or silver)

Dental amalgam used for filling teeth, comprises about 50% liquid mercury, mixed with powdered silver, tin and copper. Once mixed, it quickly sets hard, even though it's half mercury:
https://www.fda.gov/medical-devices/dental-devices/dental-amalgam-fillings

I've seen and handled mercury amalgam made from beach gold dust on NZ's South Island West Coast. A lump the size of a walnut and about as hard as a lead sinker. I don't know what proportion was gold, but it was still a silver colour.

After a bit of further research, I now have a better understanding of what you are saying hiluxer & of how mercury amalgam forms & or how or why it were left behind.

Cheers Kon

I have tested the lump of metal and even though it does scratch it is nowhere near as soft as lead. The screwdriver doesn't dig into the metal, it just scratches across the top of it. It seems that the acid forms a powdery surface which can be scraped away with steel wool and once that is removed then it is a hard surface again.

Regards Axtyr.

Did the XRF testing indicate other metals besides gold?

I was reading up on gold fire assaying procedures today and apparently the penultimate stage of that process produces a gold/lead composite button, which I guess is another possibility for your mystery slug. This button is then put back into the furnace in a special cupel which absorbs the lead when the button melts, leaving behind the gold which is cooled and weighed to determine the richness of the original rock sample.

What Is Fire Assaying?:
http://www.mine-engineer.com/mining/assay2.htm

Hiluxer, I asked about any other metals but they told me it only displayed gold content. This was back in 2014 so maybe things have changed with the technology since then.
It is a bit like linotype lead except you can gouge a channel through linotype with a screwdriver, and this is a lot duller in colour. For now it shall remain a mystery. The joyous finds from the goldfields. It is strange that I never found anything like this during the 80's.

Regards Axtyr.

Linotype - that takes me back 50 years or so! If linotype metal turned out to have 8% gold content there'd be fortunes to be made if you could find any scrap, as those machines were the mainstay of commercial printing for generations.

I'd forgotten that XRF's are target-specific and not omni-sensitive. If I remember rightly, changing one to analyse for another metal entails not just a user plugging in a different search-head, but also the services of a technician with the specialised equipment to recalibrate the instrument, because of its high sensitivity.