"were examined by optical microscopy to facilitate a...

"were examined by optical microscopy to facilitate a petrographic assessment of rock types, and also a mineragraphic scanning in reflected light to identify opaque minerals".

VG normally means that you can see it with your naked eye. In this case, it was lucky that eye happened to be behind a very powerful microscope! Better ASX announcements from other companies, show drill core with circles drawn around the VG.