A friend & fellow group member Girty made a trek to Hanging Rock to look for flint & found some! Hanging Rock is about 100 klms from Armidale New England NSW where I live, & close to Ebor & Tamworth. Hanging Rock village used to be a gold mining town in the 19th century.
This is the image Girty sent me. It looks a lot like quartz, but hard to tell from this image. Gold is found with quartz though so it is possible. Girty though assures me that it strikes sparks well from a steel. I look forward to getting a closer look at this when Girty next visits.
My thanks to Girty for allowing me to use this image, & for making the effort to find this siliceous rock.