2000 Annual Report - Heron Resources Limited

2.0 Continued
Operations Review
Goongarrie South Ore Genesis Studies
Detailed technical studies, including XRD clay analysis in conjunction with the Geological Survey of WA at Kalgoorlie, are current on
Heron’s Diamond Drill core, to elucidate the controls on mineralisation. There are two dominant ore styles.
“Limonite Ore” consists of massive non-textured, amorphous clay-goethite occurring in the upper weathering zone of the ultramafic.
Typically the ore is yellow-brown, and includes darker coloured horizons containing hydromorphic pyrolusite. The ore style and grades
are remarkably uniform. Grades typically exceed 1.1% Ni and 0.1% Co, with the peak grades at the top of the ore zone. From
geotechnical logging, the Limonite Ore is expected to be entirely soft and free-digging, with an in-situ bulk density of 1.3 to 1.8.
“Siliceous Ore” underlies and is a less leached totally gradational variant from Limonite Ore. It contains massive to vuggy
chalcedonic silica, which occurs as cellular stockworks with a dark brown clay infill. There is a sharp visual and grade boundary at the
base of the Siliceous Ore, which is recognised by a pronounced increase in MgO to above 10%, accompanied by green clay colours
and the appearance of magnesite in vugs and joints. Grades of Siliceous Ore typically exceed 0.75% Ni and 0.07% Co, and with
screen upgrading of 30-45%, leach feed grades exceeding 1.1% Ni and 0.1% Co for the life of the project can be achieved. The
Siliceous Ore should be initially free-digging in upper zones, but require paddock blasting with increasing depths. The in-situ bulk
density similarly increases with depth, from 1.8 to 2.3.
Detailed multi-element geochemistry has been completed on the Goongarrie RC drill data base to categorise ore styles:
90
Figure 7 - GOONGARRIE NICKEL PROJECT
Differentiation of Limonite Ore and Siliceous Ore
SiO 2 (Calc)
80
70
60
50
40
30
20
10
0
Scotia Dam Prospect
Siliceous Ore
Limonite Ore
10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00
FeO
During 2000, Heron completed 29 RC drill holes at Scotia Dam for 1,330 metres. Significant intercepts include:
Table 10 - SCOTIA DAM PROSPECT
RC Drilling Significant Intersections, 0.75% Ni Cut-off
Hole No. North East From To Interval Ni Co Ni4Co Ni4Co%*
m m m m m % % % x m
GSRC068 59,203 6,010 14 38 24 1.32 0.239 2.28 54.72
GSRC069 59,200 6,086 11 17 6 1.03 0.178 1.74 10.44
21 48 27 1.27 0.062 1.52 41.04
GSRC076 58,800 6,169 14 35 21 1.39 0.226 2.29 48.09
GSRC090 56,002 7,366 20 35 15 1.03 0.082 1.36 20.40
* ”Ni4Co% x m” for a drill intercept is the value of %Ni plus 4 times %Co of the interval multiplied by the intercept in metres.
A nickel sulphide target has been delineated at Scotia Dam. The anomalous interval is 18m at 2,466ppm Ni and 347ppm Cu
at the basal contact of the olivine cumulate komatiite sequence. Peak copper is 0.14%.
The eastern Scotia Dam prospect area on Siberia Formation ultramafic contains an area of 1.20x0.15km hosting a 20-78ppb Au soil
anomaly within a favourable Bardoc Tectonic Zone structural setting. There has been no systematic drill testing of the target. The
target zone is close to proposed mullock dump sites for the future Scotia Dam pit, so the gold target will be drill tested in the course
of mullock sterilisation drilling.
Heron Resources NL Annual Report 2000 page 17