Hi Jethro. Yes I did clean it with a CLR bath and then a toothbrush as the whole rock was covered in green copper sulphate. Poking through in various spots was small glimpses of quartz so I knew that the host was Quartz. In this area, no matter was has laid on the ground, it either gets covered in copper sulphate or gets eaten away by the white ants [just the nature of the area].
Mbasko, at Wallaroo, just up the road from the Maritime museum, there was located the remnants of the old smelter and acid works. The rusted skeleton of the old plant was still there up until the early 1960's but when I started work at the Fertilizer factory next door in the late 60's, it had all been demolished. I don't know what part the acid works part of the thing was about, but it was where my grandfather worked for a long time I think. The stacks of the old smelter, and some of the built furnaces can still be seen from the waterfront down by the jetty and sailing club. Great stuff if you are into all that.