So.  Let's recap what I gleaned from "ground studies".

1) The "last time" the XRF was used was in February 2018.

2) The uses with visiting geologic executives occured BEFORE February 2018.

3)  They used XRF on site tours "earlier this year" which means before February 2018.

4)  There have been no uses of XRF since February. 

5)  There is a very long monsoon season in Cochise County which hopefully will end in August.