Ann: Loma Bonita Delivers More High Grade Gold-AZS.AX, page-46

Expanding greatly on this previous post.

AZS uses the following grid for their drillholes : NAD27 MEX12. as shown in the inset below

As vague research I was plotting the LB A-A section drill holes on Google Earth when it became apparent something was wrong. They were plotting on the southern slopes of the MDP/LB ridge rather than where I expected. C90 is supposed to be on the crest of the ridge!


What was/is going on?
I looked at the AZS aerial view and attempted to photo interp those holes onto google earth. MDP19 is the only one I am reasonably happy with to be within +/-10m of the location given in Figure 1 of the announcement. There are 5 photo interp holes plotted:


Again using Geenius's very helpful tip (plus Haplo's for image colour) the photo interpreted coordinates give a profile that is more appropriate.


The spreadsheet correlates the differences. Google earth photo interpreted points relative to the drill hole coordinates. There appears to be a fairly consistent difference in Northing and Easting which could be used as a correction to plot on Google earth in the absence of the NAD27 MEX12 coords used by AZS.

Reduce the easting by some 67m
Add some 200m to the northing.

Assuming the simplistic conversion above is a linear correction then by applying this to drill hole locations at Cerros San Simon and Enmedio the following image is the result:

This a very significant variation and definitely worth further work to confirm if the grids are that different.

Perhaps there is an option in Google Earth Pro to select different grids.

Also there are probably exact conversion factors available for these different grids as well as many others.

I was doing a similar exercise for WCN soil samples when I first noticed a discrepancy between google earth and company coordinates. From memory the difference was of a similar magnitude.

As always DYOR and GLTAH