Mineralisation was identified at Gladstone Hill as far
back as the late 1870s-early 1880s, shortly after the initial discovery of
mineralisation at what is now the Martha Mine. Indeed, early recovery problems
associated with the Martha mineralisation led to the preferred development of
ore bodies within what is now the Union Hill Joint Venture tenement; ore bodies
such as Silverton, Amaranth, and Union to name a few. Gladstone Hill forms the
basis of the Union Hill Joint Venture, a 50:50 joint venture managed by Au-Ag
Resources Ltd (a fully owned subsidiary of Otter Gold Mines Ltd), and Welcome
Gold Mines Ltd (a fully owned subsidiary of the Normandy Group). The joint
venture participants also operate the adjacent Martha Mine.
Mineralisation of Gladstone Hill, as with mineralisation
at the adjacent Martha Mine, has been interpreted as a low sulphidation
epithermal Ag-Au system hosted within hydrothermally altered andesites of the
lower Coromandel Group.
Drilling in recent years has successfully identified
extensive mineralisation associated with a number of vein sets throughout the
tenement including the Gladstone Vein set, the Moonlight Lode and more recently
along a north-easterly trend towards the historic Favona workings. A wide range
of vein styles is apparent, ranging in character from thin stock works to
broader lode-style banded chalcedonic to cherty quartz and have been interpreted
as representing multiple phases of emplacement. At shallower levels
mineralisation is often hosted by vein clasts within vent breccias. Visible gold
is rare, with mineralisation generally associated with very fine-grained pyrite,
arsenopyrite and minor electrum. Percentage levels of combined
sphalerite-galena-(+/- chalcopyrite) have been intersected at depth however
these have been gold poor to date.
The potential for the Gladstone Hill area remains to be
clearly defined as drilling to date has yet to close off mineralisation both
along strike and down dip. If further drilling is successful, the joint venture
partners believe Gladstone Hill could contribute significantly to the economic
future of current operations.