Ann: High Grade Copper and Gold Identified at Big One, page-60

It just means that the instrument is possibly detecting some gold in those surface specimens portable XRF has a lower limit of detection of say 5ppm and whatever the element is - when its down at the limit of detection the results are notoriously unreliable.

As another poster implied - the way that XRF's work is that their gold detection can be prone to "interferences" or wavelength patterns from other worthless elements such as arsenic, tungsten, and zinc, which are quite common in iron rich gossans, so you can often get false positives in rocks that seem to have gold, but when the results come back from the lab its invariably the case that the gold just isn't there or is much lower grade than the portable XRF is indicating.

For base metals such as copper, lead and zinc the XRF is great - for gold - the technology is not quite there yet.

Here is a good well written link about portable XRF for those interested (probably better explained than how I can do it):

https://www.azomining.com/Article.aspx?ArticleID=1333#:~:text=Portable XRF also suffers from,results or conceal gold detection