Xtract Resources– Bushranger – Hole 1 920m @0.3% Copper.
Well, we have the first assay results for Xtract Resources
(XTR) on the Bushranger prospect in Australia.
Porphyries are not easily understood by the market and the
response from XTR has unfortunately, not been the exception.
There is no doubt that Bushranger is a copper porphyry. What
I mean by this is that this porphyry is dominated by the later, copper rich intrusions,
which have overwritten the early barren or gold centric intrusions. There was
much talk about mineralisation evidence of the kind of quick fluid cooling that
leads to a gold rich, copper reduced porphyry. However, it is clear that this has
been over-written by the later copper stages of intrusion action.
For simplicity sake, also for the cheaper capex, being just
copper rather than a small copper and gold, is probably an advantage.
Moving onto the geology of the later section of the hole. We
still find solid, if not spectacular copper grades. At first glance this might
be concerning, we expect copper and gold to increase at depth. However, we know
that the best mineralisation results are in the alteration zone next to the
intrusion. Hole 1 was drilled to intersect this mineralisation, using the
location of the intrusion from the existing JORC and to see if it continues.
The problem is that a drill, operates in a straight line -near enough,
therefore when the intrusion plunges or flatlines, as per fluid dynamics, it is
impossible to remain in the sweet-mineralised area. Particularly if you are
going to drill over 1km in length.
It looks like the mineralisation has travelled at a
shallower dip from around the 500m mark, meaning that drill 1 passed through
the outer mineralisation zone from about 500-600m to EOH. Hole 5 and 6 will be
crucial in understanding this depth, particularly hole 6.
If we look more closely at the results, we can see that the
top section 110m – 550m 400m is 0.42%. This is important, as any development or
commercial decision of Bushranger, will be split. The common method of developing
these systems in Australia, is to open pit down to the 500m level and then undertake
targeted underground mining. With this known, the top section of mineralisation
needs to be good, and 0.42% is more than good enough. A comparison to Rio Tinto’s
Winu is useful here.
We know from an internal Anglo American Geology report, that
more than a single porphyry exists at Bushranger. The below is a sample I’ve taken
from that geology report that talks about Porphyry 2 at depth and in the outer
northern edge of their Bushranger drill program in 2014-2015.
“"Porphyry 2:
Kspar+Plagioclase+Biotite-phyric Dacite Porphyry
This distinctive porphyry unit is present in
TBRC030 @ 315.8m in contact with volcaniclastic
sandstone, and @329.6m, and@335.2m), in BRC032 @
221.8m and @217.65 where it clearly
intrudes the monzonite), and in BRC034 (@
169.3m, and @224.4m where it occurs in contact
with Porphyry 1). It also occurs in hole
RACED020 where it is clearly intruding a volcaniclastic
siltstone.
This porphyry is distinctive in having large (to
almost 1cm long) blocky Kspar phenocrysts that
often include one or more small plagioclase
phenocrysts."
Given this and the alteration, porphyry mineralisation
observed from as little as 50m depth in holes 5 and 6, we can assume that the
second porphyry intrusion has an outer alteration zone that extends near to surface.
Later assays will need to support this, but a safe assumption is that the
second porphyry is also copper rich and will add to a potentially 1km east to
west and 2km north to south open pit potential to 500m depth.
With this level of mineralisation, XTR should have no
trouble increasing the JORC -after a planned infill program- to trigger the 2mt
of Copper that requires Anglo American to buy 80% of the project. The company
has talked about further IP surverys etc, but a second drill plan should complete
a new, trigger JORC by the end of the year.
XTR has talked about finding new nearby porphyries that can
attract an economy of scale in the same vein as the Cadia-Ridgeway grouping.
There is no doubt that further funding will be needed to
complete the infill drilling and JORC creation of Bushranger to the 2mt mark. Whether
that funding is created by the revenue streams of the African projects, via
share issue or even by a partner coming on board for a cut of any sale price is
largely immaterial for 2021.
So, to conclude; Bushranger this year will -very likely-
become the second largest single copper deposit in the Lachlan Fold, behind
Cadia East. The Rockley-Gulgong sub arc belt within the Lachlan Fold, was the
sub belt that formed last in the geological history of the Fold, and as such,
looks like the intrusions in the area will be predominantly copper rich. Just
as Cadia is the gold work horse of the Fold, so the license areas held by XTR –
which is the majority area of the Rockley-Gulgong volcanic area- looks to be
the copper workhorse of the Fold. The unique characteristics of the sub belt leaves
Bushranger and XTR in a unique position in a copper demanding world. If I can
recognise that sat here thousands of miles away, I have no doubt that the copper
experts in Australia do too!
