Mineral Analysis

[Micropedes1]

I have been digesting and running last year’s samples thru ICP-AES for most of a month now. Very time consuming. I keep thinking that there has to be a better way to see mineral composition without carrying sacks of rocks home.

Some of my off-line conversations with Jim has caused me to resurrect my experimentation with laser-induced breakdown plasmas (LIBS). I am hoping to creat a small enough unit for in-field analysis.

Anyone on here with LIBS experience?

[Jim_Alaska]

I've got some rocks like that. Seems I always have good intentions, but never get to even crush them to get a look.

The LIBS should be an interesting project. I have done ambient air breakdown, but never had occasion to go on to anything else.

Here is a pic of a simple air breakdown I did as a laser research technician. It's kinda small, but perhaps you can get an idea.

Airbreakdown.JPG

[Micropedes1]

Thank you, Jim. I needed a jolt to get me back on track.

I already have seen proof of concept in a lab setting. Just need to build my own. SciAps has a hand-held version on the market. I looked. Prohibitively expensive, even to rent. Not sure I can minaturize enough for that degree of portability. Would be happy with a larger, portable version.

[Jim_Alaska]

Yes, the main problem will be scaling it down. The pic I posted was using a quite large Spectron dye laser, minus the dye for this air breakdown. I only needed the power to actually ignite the ambient air, that's why the laser is emitting green light instead of yellow for Na.

[Micropedes1]

I was running a double pulsed carbon dioxide laser which marginally met my power requirement. I just ordered a Nd-YAG upgrade that is more powerful and much, much small. Expensive though, even used

[Geowizard]

laser Ablation;

https://appliedspectra.com/technology/libs.html

The method does an assay on a .2 mm surface "spot"...

This could be problematic for bulk assay of GOLD ore that may not have a nugget in view.

- Geowizard

[Micropedes1]

Running double pulse gated 10 ma between pulses to minimize “matrix” effect. 1028nm frequency.

Getting results comparable to lab-based AES. Repeatability issue as solid samples not as homogenous as acid digested fluid. Gold is not the only one tested for. But 3-4 quick samples with a LIBS device will quickly tell if more extensive “wet” testing is warranted in the general area.

Nuggets? Not much chance of that. And for that an XRF device works just fine.

Wonder how much of this can be used toward annual labor requirements?

[Jim_Alaska]

I believe that ANY work done ON CLAIMS will qualify as complying with annual labor requirements. It may even comply if the analysis includes gathering and transporting samples from your claim to a remote lab (your house)