Hey guys,
I just love getting out there and seeing what nature has to offer. I have a log of samples and was wondering if any of you folks could recommend a lab for fire or photon assays on rock samples?
I'm in South East Queensland.
Regards,
Caleb
I used to use ALS in SE Queensland years ago. They are still around and reputable. I don't know your background and you may well know the following, but if so it might be useful to others.
Unless you have a lot of money to spend and quality is not important, think about WHY you are doing the analysis - what is your aim? Not all analytical techniques are equal. For example, there are cheap methods available to just get some idea of how much gold is in a sample, but they are analytically precise but not accurate i.e. they will consistently give a similar result, but it may not be very accurate (eg I have experienced analytical gold values systematically a third lower than fire assay). Sample size often makes a sample unrepresentative (e.g. some techniques are only used on a fairly small sample using an aqua regia acid attack, eg AAS, ICP). For example, on grams rather than half a kg (the latter possible with proton analysis). Remember when you give a lab a sample they are usually not analyzing the entire sample, they may just analyse a tiny bit of it - one reason why sample prep is expensive, because that tiny bit needs to be made representative of the whole. But a low level of accuracy may suit your purpose (eg if you are just submitting "a lump of rock" rather than a sample made of systematically-collected material that is representative of the site you collected it). You might just want to know if an "interesting" amount of gold is present (e.g. grams per tonne = parts per million, rather than only parts per billion).
Photon assays are great in general - you can analyse a large sample (at least as large or larger than with a fire assay) at good analytical accuracy (so if you have sampled accurately it will give an overall accurate result), and there is less sample prep (which is expensive). However samples with elements like barium in them will give inaccurate results (common in gold deposits in coastal and North Queensland and even parts of east coast NSW). Uranium-bearing samples have the same problem (eg around Cloncurry, and particularlty in South Australia with iron-oxide copper gold deposits similar to Olympic Dam).
In which case old-fashioned fire assay may be best - it is accurate and uses a fairly large and representative sample.
Best to talk to your analyst first and not be too secretive about the area the sample is from.
