loamer said:
In the 1908 Mines of SA Book - Olary - the rock formation is gneissic micaceous granite, mica slate etc with eruptive granite. (Granite inclusion I suppose) it also says there are numerous quartzose and ferruginous reefs which appear likely to contain gold. In 1889 it was reported that a strong lode could be traced fully 2 miles bearing E.N.E. If you have the book - page 185. It is one of the best books I have ever seen.
PS. Excellent posts, questions and follow-up by the way!
Hi loamer
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gneissc( pronounced like the biscuit, nice) and granite are the same in essence, and bloody hard, gneiss's mobs scale varies on the sample, yet to see one under 7, and mostly in the 8, 9's.
gneissic micaceous granite, means looks like mica, will have a slate type appearance, with a low hardness. Mica can rate from 1.0 to 6.0 on moths, and for a comparison you may recognise, quartz is 7.0, so this formation could be as soft as talc, or almost as hard as quartz.
mica slate, again this is pretty wide by todays standard, by given that the area was subjected to high heat during it's history, I would expect that you will find poorly formed slate.
eruptive granite, oh this means stay away, essential it means the sedimentary rock in the are was subject to intense heat and pressure. I don't have the surface geo map for the area but I bet there are a few faults, and if you could lay you hand on a geo map with strike and dip, it would be littered with them. Basically this gear, needs to be drilled and blasted, it's hardness and resistance factors are so high, the hydraulic hammers on excavators, they just melt their moils trying to break it.
ferruginous reefs, containing iron oxide, so normally they would list the main component of the reef but if the description is right, then you would be looking for red calcium, or iron ore thats been subject to intense heat and pressure, sounds weird personally, and wouldn't be the first time an surface geo map had a bad description. Hope you have a high end detector, sounds like the mineralisation will play hell in that area.
Go prepared, Good luck