Help identifying a find please.

Hi I posted this in the Finds Identification and Valuation section but it has been suggested that the Lapidary experts may have a better idea of what this find is.

I was wondering if anyone could help me identify this odd looking nugget-like find (or perhaps help point me in the direction of some service that could).

The find is about 8mm long and heavy. It has a soft outer brown layer with the density of bread that is easily scratched away and smells a little like sulphur. When looking at the brown layer under a microscope the occasional tiny ruby red crystal can be seen growing in its pores.

Please excuse the poor photos of the find under the microscope but it was the best I could do.

When the find is cut in cross section you can see the brown outer layer. Within the outer layer you can also see white spherical hollows and in those hollows it looks like white crystal hairs have grown towards the centre of each sphere.

Moving inwards you can see the mottled soft metal core. There seem to be at least two soft grey metals mixed together (lead & ?) but also a red/gold metal seems mixed up in it too (sorry the photos don't show that detail).

When I first dug it up from about 20cm down I thought it was perhaps a bullet. When I saw it was mottled I thought it may be a bullet mixed with say carbon from a fire. However the odd outer layer and the red/gold additions have me baffled. It wasnt found too far from Maldon so I thought perhaps it could be Maldonite but again the outer layer seems odd.

Has anyone seen anything like this?

Thanks for any help!

Interesting.

Is the streak colour a greeny-black?

SneakyCuttlefish said:

Is the streak colour a greeny-black?

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Under several light temperatures on a white background the core colour is a reflective pewter grey. The surface could be said to be a greenish-brown. When they mix therefore it is a reflective grey with greenish-brown overtones.

You could do a specific gravity test to give you a better idea as to what it is. :Y:
I don't know what it is though, sorry :|

I wonder if you would be better off asking the gold guys in the gold prospecting section. Those blokes know their metals.

My guess is massive form chalcopyrite. If you drag it across a white tile the streak should be greeny-black and it will become magnetic when heated. Best way to be absolutely sure is to send if off to SGS or another lab and have it essayed. Costs a couple hundred dollars but they send back a report with the full break down of all the elements and what concentrations they are.

Jack's Gems said:

You could do a specific gravity test to give you a better idea as to what it is. :Y:
I don't know what it is though, sorry :|

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Thanks Jack, it is heavy but given what looks like multiple minerals I don't know if a gravity test will tease out all the components.

SneakyCuttlefish said:

send if off to SGS or another lab and have it assayed.

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Thanks SneakyCuttlefish. The more I think about it the more I realize that its all just guesswork and I want to know for sure what it is.

Do you know whether a lab will give me a common name like Aircraft Aluminium Alloy or will I just get back a breakdown of various percentages of say Silicon, Iron, Copper, Magnesium etc. Also if it say IS Maldonite then would they tell me it contains Au2Bi or would they just say it has x% of Gold and y% of Bismuth?

Sorry if these are silly questions my chemistry is poor!

Last time I had an essay done I only received a break down back. If you ask for an official identification I am sure they can do it. Not sure what the cost will be though.

Maldonite said:

SneakyCuttlefish said:

send if off to SGS or another lab and have it assayed.

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Thanks SneakyCuttlefish. The more I think about it the more I realize that its all just guesswork and I want to know for sure what it is.

Do you know whether a lab will give me a common name like Aircraft Aluminium Alloy or will I just get back a breakdown of various percentages of say Silicon, Iron, Copper, Magnesium etc. Also if it say IS Maldonite then would they tell me it contains Au2Bi or would they just say it has x% of Gold and y% of Bismuth?

Sorry if these are silly questions my chemistry is poor!

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Not silly questions - quite sensible. They will just give you a breakdown of the % (or ppm) elements in it (silicon, iron etc) - however it is not too difficult to determine the compound from that (e.g. Au2Bi). 1%= 10,000 ppm (so 3000 ppm Au would mean 0.3% gold). Also, the analysis may at least tell you whether it is artificially made or a natural mineral (many compounds don't occur in nature).

With chemical analysis I would analyse each different component, or failing that the central stuff (in its core). The best way to determine things like this is by analysis under a quantiative scanning electron microscope, but it is pricey. Alternatively minerals can often be guessed by a simple X Ray diffraction image without actual chemical anmalysis, but again not cheap (but cheaper).

Without your own laboratory I would look at the central stuff, note its colour, hardness and streak, and determine its SG (easy and cheap).

The outer layer is possibly formed by weathering of the core. I don't think it likely to be maldonite (nor chalcopyrite). And lots of wierd minerals occur near Maldon!

Maldonite, why did you choose that monicker (I ask because I am looking at maldonite at present)? You are very unlikely to find maldonite either in the granite at Maldon, or more than a kilometre from the outside contact of the granite, and it occurs in the same places as gold (eg you might find it on old mine dumps). It forms when the granite cooks up the gold-quartz veins and adds bismuth to them - but that only occurs close to the granite contact.

And of course you can look up the composition of minerals on line and compare them with your analysis - or ask here.