Intrusive rocks like granites and pegmatites are absent from your immediate area, and gold miners used to record gems when they were seen (but did not record them except around Donnelly's Creek and Walhalla-Erica- those probably came from gravels beneath basalt flows that occur there). Brownish sapphires have been recorded from Stringer's Ck at Walhalla, with zircons and topaz to 2 cm of poor colour - also west of Erica with some black spinel (perhaps derived from the Baw Baw range and minor basalt flow remnants).
While dykes are present they are not the felsic (granitic) type that host gems. I did my Honours degree on dykes of the area, later explored some dykes for gold, and I later worked there hunting concrete sand for the Thompson-Yarra diversion tunnel.
So while there is always a tiny possibility of gems anywhere, I would class it as a very poor area for gem prospecting. Chances might be slightly higher around the Howqua area (e.g. jasper on Blackbird Creek and north at Tatong). The exception is clear quartz crystals up to 10 cm long (Morning Star, A1 mine and in soil in a track cutting near Matlock. The Crystal King mine NW of Mansfield had the best quartz crystals in the State, and good coloured tourmaline occurs around Wombat Ck farther west (with good topaz to cms size).
There are places just outside the area - I have found numerous good blue sapphires at Toombullup (but small) with large topaz, some zircon and large garnets of attractive red (Middle Ck), and diamonds are reported there. Much farther north (Greta South area) attempts are being made to mine torquoise. The only areas that I would personally bother with are Toombullup and Mt Wombat-Strathbogies. A fairly long way from where you are but more rewarding and easily accessible.
Good luck.
can anyone provide any help or info on where I could head? I hiked for about 6 hours today to get a feel for the area and found so many promising signs all over the landscape low-grade Quartz erupting out of the ground!
