Help with strange rock

[agriff]

Hi Folks. I am in possession of what I thought was a possible meteorite. XRF revealed the following. Gold 975 ppm, Silver 1606 ppm, Platinum 608 ppm, Rhodium 242 ppm, lead 949 ppm and Iron over 10%. Very heavy and magnetic specimen over 5000 grams with specific gravity of 3.5. Any suggestions on what this might be would be helpful.

 

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[Kray Gelder]

Slag.

 

[agriff]

Thanks Kray. Slag was always on the list but visible metal flakes threw me off the track. Now I wonder what was being smelted as the rock still contains a fair amount of precious metals. Al

tjousa

 

[Plumbata]

It looks slag-like but I've never personally seen material quite like that. If it does indeed contain respectable and even concentrations of precious metals throughout the specimen then the only thing that comes to mind is that it's a by-product of the Lead mining that went on in that part of Illinois in the 19th century, as lead ores often have trace PMs mixed in, but I don't really know the specifics regarding the ore smelting process or the by-products they discarded. I could see it being impossible to economically recover the PMs in the mid 19th century, but concentrations of just the gold at 1 gram per kilogram sounds pretty worthwhile with today's technology!

Assuming those analysis results are uniform and replicable that is some fascinating material you've found!

 

[agriff]

Thanks Plumbata. This has had me confused for the past 6 months. I grew up near Galena Il. and have seen a lot of lead smelter slag. Not similar. I came across this mystery rock in New Mexico. I can except slag but I am still scratching my head

 

[A2coins]

Post it on rock and gem forum you never know

 

[A2coins]

Welcome also

 

[Kray Gelder]

Thanks Plumbata. This has had me confused for the past 6 months. I grew up near Galena Il. and have seen a lot of lead smelter slag. Not similar. I came across this mystery rock in New Mexico. I can except slag but I am still scratching my head

I'm just guessing at the slag ID. It seemed with those percentages of ore....curious where those numbers come from....it just sounded like float from the first run of crushed material.
Probably an older smelter, I doubt modern operations let that get away. WAG here.

 

[agriff]

Thanks for the welcome. I thought I was on rocks and gems. ? Still new here so I could have misplaced the thread by accident. I might send it to the meteorite forum but I don't want the waste anyone's time.

 

[agriff]

Thanks again Kray. Have looked around for expected PM concentrations in primary crush/smelt and secondary. Nothing fits yet but I will keep looking. Rhodium is throwing me a curve as it is primarily associated with platinum smelting but it's hard to believe they would leave that much platinum on the table.

 

[agriff]

For everyone. The concentration of metals was conducted by a commercial firm for a fee. Those metals listed in my original were everything. No other metals!

 

[Clay Diggins]

For everyone. The concentration of metals was conducted by a commercial firm for a fee. Those metals listed in my original were everything. No other metals!

I'd ask for my money back. Those are bogus numbers. The gold numbers are silly, miners have had the ability to efficiently extract gold in smelter slag for more than 150 years. Any claim of significant Platinum group metals in either New Mexico or Arizona are a scam.
New Mexico (PDF)
Arizona (PDF)

XRF is not a reliable "assay" method and is not used for commercial assays. Pay the $50 for a genuine fire assay and I'll bet those high metal values melt away like ice on a southern New Mexico summer day.

 

[agriff]

Sounds like great advise Clay. I have been researching this since the numbers came in last week and the numbers do not make any sense. Time to take a breath and rethink. Thanks to all.

 

[ecmjamsit]

I would say slag from really old smelter. Maybe as old as a Spanish mining operation. Here in Colorado I come across old mining operations leftovers. What is unusual is why one side is flat. Looks like it was against some kind of wheel or rotational equipment. Where exactly was it found? Was there a lot of it? Near any railroad tracks? The first mills out west were very experimental when it came to refractory ores. That is why the Cripple Creek discovery was not until 1891!

 

[agriff]

I am a bit short on information as the 12 lb. rock and 2 smaller one were given to me who in turn had them given to him. The original owner was an old rockhound but no one knows where they were first discovered. Likely not far from southern new mexico as it would be very inconvenient to carry around. Yes there are three in my possession and one more larger one I did not get. There are a bunch of very old spanish silver mines in the area we visited . Maybe, just maybe. And i need to apologize and clarify. The flat side that was mentioned is a 26 gram slice I removed for examination. Thanks

 

[agriff]

Thanks for the help. In order to prevent hyperventilating over this silly rock, I have sent a sample to a major university for an opinion. Thanks y'all.