Myrtle Deposit Geology

The Myrtle prospect was located in 1966 by Carpentaria Exploration Company (“CEC”). Hole MY1 intersected 35.7m @ 0.6% Zn, 0.09% Pb and 6 g/t Ag, and the prospective Barney Creek Formation was recorded to be over 100 metres thick. Further work then included geological mapping, rock chip sampling, gravity geophysics and further drilling (holes MY2 – MY5), resulting in the delineation of a number of subsidiary sub-basins within the Myrtle area.

No further work occurred until 2004 - 2005, after North Mining Limited acquired the ground. Drilling of holes MY6 and MY7 by former JV partner Anglo-American Plc intersected low-grade zinc mineralisation, similar to that drilled previously in hole MY 1.

It wasn't until hole MY8 was drilled, and intersected a wide interval of moderate grade mineralisation, that it was realised that holes MY6 and 7 were not deep enough, and so they were deepened, subsequently intersecting high grade mineralisation towards the base of the HYC Pyritic Shale Member. Holes MY10 and MY12 have also intersected mineralisation, and shown that the prospective mineralised horizon is widespread.

Anglo-American reported in 2005 that they had defined the limits of a major hydrothermal system of at least 3.3km x 1.6km (> 5.3km2), recommending detailed infill drilling, in particular to the north and south of holes MY6 and MY10 to define the highest grade central part of the system.

The region extending from Mt Isa in the southeast through McArthur River and for 500km to the northwest is probably one of the most well endowed zinc-lead regions on Earth. Myrtle now takes a place amongst the top 10 SEDEX zinc deposits in Australia (see table below). it is probably the most significant zinc deposit discovery for some 20 years or so (since the discovery of Century in 1990).

 Mt Isa - McArthur River Region

 Table 1: Giant Sedex Zinc Deposits in Australia

Deposit
Mt Ore *
Mt
Zn + Pb
McArthur River
227
30.4
Mount Isa
150
19.5
Hilton
120
20.3
George Fisher
107
17.7
Century
95
14.1
Dugald River
48
6.8
Cannington
44
7.0
Myrtle
37
1.9
Lady Loretta
14
3.1
Pegmont
9
1.0

 * Based on published pre-mining resources as listed in Leach et al, 2000, Economic Geology 100th  Anniversary Volume

Reward EL Geology and Prospect Locations

The geological sequence at Myrtle is similar to that found at the McArthur River deposit; the uppermost unit is the Reward Dolomite, which is underlain by the Barney Creek Formation (which includes the HYC Pyritic Shale and the W-Fold Shale), the footwall unit is the Teena Dolomite.

At Myrtle, and at McArthur River, base-metal (zinc and lead) mineralisation occurs within the HYC Pyritic Shale and the mineral bearing sequence occurs over an extensive area.

 Drill Cross Section A - A'  at 8167000N

Drilling to date, which is wide spaced but over an extensive area, has shown that the Myrtle deposit has the potential to be very large and Rox plans to drill out the deposit to determine its ultimate size as time and funding permits.

Myrtle Prospect Drill Plan, showing interpreted geology, resource outline and soil anomalies

Myrtle Prospect Soil Sampling Plan