1.5% diference between XRF and assay analize?Is it normal?

[Shuny]

Hy there,

i just come one week ago from me refinery from Europe wich is not LBMA reglementated where I sell the gold and I don't know what to believe any more ,we make a test with a Fischer X ray machine and the results was 644.2 and 644.0 witch was the result and of my simple calculation -2% of the scrap gold .After one week when the test from the assay analize came today the result is 636.3 .....I stod there when the melting was dome ,we have melt it very good.On the offical webpage of the fischer they say that the machine can have an error of 0.5/1000 .
Is for the 3 time when the assay analises is smaller then the x ray machine.
What to believe? Should I change my refinery?
Sorry for me English,any help is apreciated.

 

[Dan Dement]

Shuny,

There can be lots of things that can cause the difference. First: how was it melted? Did they run a pin sample? Did the sample come from when the metal was being melted or did the crucible get pulled out and tilted 45 degrees and pulled from the middle? All of those factors can make a difference in how the XRF report comes out. Did you keep a piece of the Pin sample to have a seperate test done? I am on my third XRF machine and has a "Full Alloy" machine coming on the 15th. I have seen metal moving around in a bar as much 3%. The amount of Zinc can have a big effect on the readings. If you will PM me your email, I will send you a XRF study that I did which might give you some insight.

Dan