Hi Dave. That is what I was looking for when I was in there. If you go back to the first photo, in the right hand corner come back to the left just a little & you will see a white line of stone. That is quartz. 
The grey lines in it could quite possibly be silver/gold sulphides.
Bit like this sample that is from the Golden Cross mine, Waitekauri, when Coeur Gold were mining it. I was given this sample by the assayer who lived over the road from my ex mother in law.
I can’t recall what it assayed per ton but she said it was quite rich. The black/blue grey is silver sulphide & in the dark black lines with the aid of an eye glass you can see gold specks & smudges of gold.
It is what they called Rainbow quartz.
These ones are from The Talisman mine, Karangahake. This piece I found on an old waste dump. It nutted off on my old Garrett coin detector.
This one a diamond cut sample from the Talisman Mine. Similar to the Golden Cross stuff.
This one I found up the Thames coast somewhere up in the hills. It too nutted off on my detector.
I have some pics of the Golden Cross mines underground working face on the quartz reef from when I was went under ground with a friends father who worked there. I think they are on old school 35mm film. I will try to hunt them down & copy them & post them up.
Cheers
JW 