Assay cup

[vegasjames]

Here is an assayer's cup I found recently near a mine in Goldfield, Nevada.

[Deleted]

Is that slag or lead in the cup?

[jakesrocks]

Cool find. That could be lead or silver. I have a couple slugs from the bottom of assayer's cups, but was never lucky enough to find an actual cup. Also a couple of old carbide miners lamps. One is crushed from a cave in.

[jamesp]

What is an assayer's cup?

[jakesrocks]

An assayers cup was used to melt raw ore, to determine the content and weather enough of the target precious metal was present in the ore to make mining it profitable. The cup was usually cooled and broken away from the melted blob in the bottom. To find a whole cup with most of the melted ore is pretty rare.

[jamesp]

That is a cool find. Thanks for the knowledge

[vegasjames]

Jun 28, 2013 19:07:21 GMT -5 @shotgunner said:

Is that slag or lead in the cup?

I did not lick it to find out.

I would say slag.  The mines in the area are primarily gold or copper mines.

[Deleted]

Wasn't lead used in the assay of gold tho'?

Fire Assay & Cupellation

Cupellation: the lead bullets are placed in porous crucibles (cupels) of bone ash (MgO) and heated in air to about 1000°C. This is usually carried out in a 'muffle' furnace, containing a refractory muffle (usually nitride-bonded silicon carbide) heated externally by silicon carbide heating elements. A flow of air through the muffle assists oxidation of the lead, and carries the fumes for safe collection outside the furnace unit. The lead melts and oxidises to lead oxide, which in turn melts and is drawn into the pores of the cupel by capillary attraction. The precious metals remain in the base of the cupel as a 'prill' which is sent for final analysis of precious metal content.

I asked it if was lead because if there is you may have some gold there too!

[jakesrocks]

Jun 29, 2013 1:26:53 GMT -5 vegasjames said:

Jun 28, 2013 19:07:21 GMT -5 @shotgunner said:

Is that slag or lead in the cup?

I did not lick it to find out.

I would say slag.  The mines in the area are primarily gold or copper mines.

Quite often silver is found with gold, along with several other metals. Each has its own melting point. As the molten metal and rock slag cools, the various metals will form layers. The rock slag being lighter than the metals will rise to the top and cool as a glassy slag.

[vegasjames]

Jun 29, 2013 10:49:18 GMT -5 @shotgunner said:

Wasn't lead used in the assay of gold tho'?

Fire Assay & Cupellation

Cupellation: the lead bullets are placed in porous crucibles (cupels) of bone ash (MgO) and heated in air to about 1000°C. This is usually carried out in a 'muffle' furnace, containing a refractory muffle (usually nitride-bonded silicon carbide) heated externally by silicon carbide heating elements. A flow of air through the muffle assists oxidation of the lead, and carries the fumes for safe collection outside the furnace unit. The lead melts and oxidises to lead oxide, which in turn melts and is drawn into the pores of the cupel by capillary attraction. The precious metals remain in the base of the cupel as a 'prill' which is sent for final analysis of precious metal content.

I asked it if was lead because if there is you may have some gold there too!

Lead has a sweet  taste, which is why the Romans used to lead their wine.   But as I said I did not lick it.  Actually beryllium has a sweet taste as well.  Some people looking for beryllium ores will lick the ore to help determine if beryllium is present.  Probably safer to lick the lead.

But there is the glassy crust of the slag so I would probably have to destroy the cup to see what button is inside.  I like the thing though so I will leave it as is.  Maybe I will have XRD/XRF done on it someday to find out the secret of what it contains.

[jakesrocks]

Good call to leave the cup as is. Hope you got the GPS location of the mine, so you can put a mine name with the cup. It's a piece of mining history.

[vegasjames]

Jun 29, 2013 12:28:13 GMT -5 jakesrocks said:

Good call to leave the cup as is. Hope you got the GPS location of the mine, so you can put a mine name with the cup. It's a piece of mining history.

I went back a week later looking for the mine again because I wanted to look for more artifacts.  The cup was down in a pile of rocks where they had been throwing a lot of trash.  There were pieces of old bottle, lots of tin cans, pieces of mining equipment etc.  The cup was laying on the ground between some rocks.  So I figured if I move some more of their rock pile I could find some more artifacts.  I did not find the mine again though.  I was in the general area and I am sure I can find it again given a little more time so maybe in the fall I will go back up there and spend some more time looking.  All I have to do is go up higher on the road to the mountain because the mine was easily visible from the road at the base of the mountain.  I just did not go up as high this time because my vehicle does not have as high of a clearance as my friend's truck we went in last time.

[jakesrocks]

Cool. I have a few artifacts from the old Black Jack silver mine, near Amboy, cal. I dug them out of the tailings pile right in front of the mine headframe. The miners lights were found in and around a mine near Calico Ghost Town back in the 50's. BLM blasted all of the entrances to those old mines for safety reasons, but they were wide open when I was a kid, and kids are fearless. lol