purple fringing & chromatic aberration

Hi Guys,

I have read with interest most of the posts about purple colours in the ICG drill core pics, especially the most recent pics published on 14Feb2013 where the quality of the photos shown is fairly poor overall.

Firstly, let me stress that I am not attempting to say here that there is bornite, or that there is no bornite, in the drill core presented in these photos.

What I am saying is simply that the most likely explanation (IMHO) for most of the purple (and also green) tinges in the 14Feb drill core pics is what is known in photography as "purple fringing". This is partially caused by "chromatic aberration". For an explanation of this, and some sample images, you can look up "purple fringing" and "chromatic aberration" on Wikipedia. Happy reading/researching ! ...

If you would like to see an example of the above aberrations that is directly relevant to ICG, check out page 1 (Figure 1) in the ICG announcement from 14Feb. Locate the last (EOH) core box, which is marked "h)". Have a look at the lower (grey) section on the right hand side of the "chequered flag" board above the core box. Zoom it in to around 800%. You will see, particularly on the far right, that there are distinct purple and green areas on what would otherwise appear to be simply "a grey area" (which in turn I think appropriately describes the problem with trying to prove anything in particular via interpretation of these photos) ...

Rgds, W.