First interesting finds! and Question re identification

[user 4386]

I have always struggled with getting much useful info from density since when faced with a heavyish-for-size lump of grey metal my question is mainly is it silver or is it lead.

SG of Pb=11.4 & Ag=10.5 so a 5g nugget of lead has a volume of 0.44ml & silver 0.48ml. Even a 30g nugget is 2.68ml vs 2.86ml

Good luck measuring to 0.04ml or even 0.18ml precision on a measuring cylider with a diameter big enough to take your nugget & even if you get a result you believe to be an accurate SG then so what? - with the strong likelihood that the silver or lead is alloyed the SG you get is not that helpful in differentiating the two metals.

Add in the impact of crevices holding micro air bubbles & dirt or meniscus & wetting issues if using mass of overflow methods & it is not generally not worth the effort in measuring SG on small lumps unless you suspect Pt (SG 21.5) & even then with a 5g nugget it only 0.21ml difference.

Hardness is a very strong indicator & melting point is a clincher as all Pb/Sn/Sb/Bi alloys will have MUCH lower melting points than any grey Cu/Ag/Au alloy (which would have to be at least 70% Ag to be grey).

Rare to get natural native silver lying at surface - it rapidly oxidises to things like chlorides. Agree re crevices etc but a lot of things other than Pt can still be determined (eg W has same SG as gold}! And is a lot more common than platinum. Don't know why you are using a measuring cylinder though.

 

[jethro]

Some Years Ago I was detecting just north of Maryborough Vic near the Nuggety Gully Reservoir and started turning up lumps of nugget shaped lead of about 410 grns give or take. When I got home I did a bit of research and found I was about in line with the old rifle range track from the late 1800s up until WW1. The lead I was finding was from stray rounds fired from Martini Henry rifles chambered in 577/450. The standard Infantry and cavalry rifle carbine of the british empire from the 1870s until the advent of cordite powder in the late 1890s, and the adoption of the 303 british round. The nugget shaped appearance was caused by bushfires over the last 100 yrs. The infantry rifle round fired a 480grn paper patched lead projectile with a charge weight of 80grns of Black powder. The Cavalry / artillery carbine rnd fired a 410grn paper patched lead projectile with a charge of 72grns of black powder.

Footnote: I own a sporting rifle chambered in 577/ 450 built around 1880 (dated from Proof marks) Firing this old girl with a 480grn projectile and 78grns of black really gets my attention and I'm about 95kg. I can imagine that the average british infantry soldier of the victorian era probably weighed in at somewhat less than 70kg. So these rifles would have been a real handful to shoot from the prone or kneeling position volley fire accurately.
If anyone wants to have a look at the old rifle in action I have short clip of its first shots here [video=480,360]https://youtu.be/yLzvG7JqNMA[/video]

 

[SteveG]

I can't believe a Geologist is asking this question? It's lead slag.

 

[UnderEmployedGeo]

I can't believe a Geologist is asking this question? It's lead slag.

Haha you'd be surprised then how much geos don't know or have forgotten. Identification of lead slag is not on the test lol, nor is it something you generally come across in actual geological exploration!

 

[user 4386]

I can't believe a Geologist is asking this question? It's lead slag.

To be fair he asked in the first post "Just slag or a weirdly deformed bullet?????"

 

[silver]

He's only a geo.... not an all knowing god lol

 

[yellowmellow]

Molten lead