Pulled this off a recent MRT document:
I’m not sure, it’s hard to even know exactly where when they say Huonville. I can’t see anything relevant on the LISTmap Mineral Occurrences overlay.
Perhaps near the Glovers Bluff ultramafic outcrop?
Yeah, ‘Huonville’ is extremely vague. Cygnet hasn’t got anything on the Mineral Occurrences overlay either - but they’re definitely there (ref: NE Tas Gems - also the source of the image). Perhaps it hasn’t been updated in a while.
I was initially quite dubious about Glovers Bluff when you mentioned it, but as it turns out a petrology report on aplite in the area mentioned that it contained “1.90% normative corundum” - and while aplite has a grain size much too small to produce sapphires (at least prospectable ones) - it does indicate that the right geochemistry does exist in the immediate area of Glovers Bluff.
There’s no clear source in Cygnet either (I’d be pretty confident saying that they are likely unrelated to the gold/copper mineralisation) which perhaps suggests some buried source? And Cygnet is really the only area in S.Tas that has been extensively explored geologically (which is why Huonville was such as surprise - who would go looking there? - although Glovers might well explain it). Sadly forming a hypothesis is near impossible due to the lack of knowledge on the sources of corundum really anywhere in Tassie.
Most Sapphire in Tasmania are derived from volcano events between 45 & 10 million years ago.
Most come from the 40-45 million year ago event, but some small ones are sometimes found in the recent 10 million year ago event which produced most of the red soils of the North West and North East.
I’ve done a lot of exploring around Glovers Buff area over the years yet to see any gems ( well no blue ones ) apart from some Quartz/Calcite Crystals.
