Assaying, Microscopy, Mineralogy & XRF/XRD

Assaying, Microscopy, Mineralogy & XRF/XRD

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0.6 ppm gold in fire assay of milky quartz and XRF result of tonnes of slag (2 replies)

6 years ago
quwannar 6 years ago

Hi all,

I live in Black Sea Region of Turkey. I found huge amount melting slags that I thought it belonged to an ancient mystery mine. in order to find out which metal was processed, I sent the slag samples to XRF analysis. Results are below.

Fe; 13.3 %, Cu; 1.83 %, Mn; 0.08 %, Co; trace, Ni; 0.002 % Zn; 0.03 %, Pb; 0.05 %

Au; < 0.1 ppm and Ag; 7.8 ppm.

When looking at Au result, It seems to be under the detection limit of XRF analysis capability. They say that this means that gold may exist or not in slag. They also say that gold may be below 10 ppm or ıt won't exist at all. finally Fire assay must be done for slags. But if we theoretically consider and compare Ag result of 7.8 ppm and co-occurrence with a gold, There probably is an anomaly between silver and gold amount in the slag. So, what is the sub-limit of detection for the gold in XRF method?

I also found a milky quartz vein nearby slag heap.  I sent it to Acmelab for fire assay. The result is 0.642 ppm. No visible gold in my pan.

So Should I go for further gold prospection like drilling where quartz vein I found according these value?

Any comment would be appreciated.


6 years ago
Rheomet 6 years ago
1 like by David

Hi Erdem,

Suggest repeat the gold and silver by fire assay with AA finish, duplicate at least, and, preferably, use a reputable lab. I would also make sure that their method is validated. This would prove more prudent compared to expensive drilling based on one XRF result, a method at least questionable when it comes to Au/Ag.  

Cheers, Alex.

max skinner
6 years ago
max skinner 6 years ago

Rheomet, is correct. XRF on material this low grade is not good. I my lab, I would run control type fire assay, at least in triplicate. If it is very important I run 6 assays, throw out the high and low and average the 4, this will give you a very good assay. As Rheomet says use a reputable lab which is very important if you want a correct answer.    Max

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