Hey SB1982, I think the diagram you posted above is a narrow target.
However NTL is high grade bulk tonnage. The boiling zone appears to have permeated through a great deal of the centre of the mountain, and was the source of the historical mines. Of course there must be large amounts of high grade ore all around those old strikes which were never developed.
My diagram below is lousy but you should get the idea. Note the "telescoping" in the black sulphide layer (localized changes in pressure and temperature may cause the boiling level to migrate up and down – causing telescoping of mineral zones and vein textures). Possibly caused the old-timers to miss a high grade layer which might be at the bottom of the boiling level in Talisman Deeps.
They certainly didn't find the main quartz vein, which MUST be there somewhere.
During 1919 bores were sunk from the lower levels, Government drills being used. These bores were sunk on various angles in an endeavour to locate payable ore. Zinc, iron, sulphide and black flint were found, but all attempts to find payable ore by prospecting, mining and drilling failed, and operations ceased by the end of December 1919.
(20min delay)