St George Mining (ASX:SGQ) has intersected anomalous nickel and zinc associated with sulphides within a thick ultramafic unit with its first hole targeting electromagnetic conductors at its wholly-owned East Laverton Property in Western Australia.
The interim results from spot XRF analysis increases the prospectivity of the Desert Dragon Central prospect for massive nickel sulphides.
Desert Dragon Central is the first of six conductors to be drill tested, each of which has the potential to deliver exploration success.
The company is currently drilling the very strong Dragon 8 conductor at the prospect with another two holes planned.
“Preliminary observations of the first hole at Desert Dragon Central suggest we have encountered a broad interval of sulphides at the base of the upper ultramafic unit which includes a massive nickel sulphide stringer vein,” executive chairman John Prineas said.
“The results of this hole are very encouraging and continue to support the potential of this channel complex to host massive nickel sulphide deposits.
“There are three more holes planned at Desert Dragon Central and they are now of increased importance. The results from this drilling will be keenly anticipated.”
Drilling Results
Drill hole DDRDD0005 was designed to test a downhole electromagnetic (DHEM) conductor identified in drill hole DDD001 that was modelled as being located on the basal contact of the upper ultramafic unit of a large high MgO channel complex at the Desert Dragon Central prospect.
It was drilled to a depth of 260 metres and intersected the conductor at 203 metres, which is consistent with the modelled position of the conductor.
The drill hole has intersected two thick ultramafic sequences, which appear to be within the upper ultramafic unit modelled at Desert Dragon Central.
This is the same unit that hosts the thick interval of disseminated nickel sulphides intersected by drill hole DRAC35, that was drilled in 2012 by BHP Billiton (ASX:BHP) under the previous farm-in arrangement with St George.
Sulphide accumulations were associated with each of these ultramafic sequences. A six metre interval of sulphides was intersected from 203 metres downhole.
Preliminary assessment by XRF analysis of this interval of sulphides returned a spot value of 4.35% zinc with low associated nickel levels.
Visual observation of the drill core suggests that the majority of sulphides at this level appear to be associated with interflow sediments.
An additional interval of sulphides was encountered between 237 metres and 239 metres.
The main sulphide encountered at this level was pyrrhotite, discernible by its magnetic properties.
Provisional XRF analysis of the drill core for this interval showed a spot nickel value of 1.55% nickel from a massive sulphide stringer vein.
The geological setting and geometry of the stringer vein infers it is magmatic (i.e. primary) in nature.
This supports the potential for further massive sulphides in this ultramafic channel. Additional geochemical analysis will be undertaken to validate this.
The drill hole is currently being processed and sampled. Assays from laboratory analysis will provide a more representative analysis of the metal content of the broad sulphide zones intersected. This will provide a vector for further local exploration within this fertile ultramafic channel.
Initial interpretation of the drill hole suggests that it did not drill into the lower ultramafic unit modelled at Desert Dragon Central.
The hole will be re-entered and extended, probably by another 120 metres, to test the lower ultramafic unit.
Desert Dragon Central
The prospectivity of Desert Dragon Central was established by drill hole DRAC35, which intersected 18 metres at 0.40% nickel from 100 metres including 4 metres at 0.57% nickel from 100 metres that confirmed the presence of nickel sulphides in the upper ultramafic unit of this channel complex.
Identification of the massive sulphide stringer vein by DDRDD0005 in the upper ultramafic unit provides further support for the fertility of this unit and its potential to host larger massive sulphide bodies.
Drill hole DDD001, completed by St George in 2013, drilled into the lower ultramafic unit and encountered anomalous platinum group elements (PGE) in each of the upper and lower ultramafic units.
Anomalous PGE’s in this setting can be an indicator of proximal massive nickel sulphide mineralisation. This provides additional support to the exploration potential of the lower ultramafic unit.
The basal contact of the lower ultramafic unit is almost completely untested. It provides an additional large target surface that is separate from the basal contact of the upper unit, which has already been shown to host nickel sulphides in DRAC35 and now DDRDD0005.
Current Activity
St George has started drilling a hole to test the very strong ‘Dragon 8’ EM conductor that was modelled by Newexco.
The conductor has a time constant of 190ms and a conductance of 3500 Siemens, which are consistent with an electrical response from a massive nickel sulphide body.
This EM conductor has a relatively short strike of 500 metres, and intersects the western margin of a positive gravity feature.
The gravity anomaly is interpreted to reflect dense sulphide-rich rocks, which may include nickel sulphides.
St George plans to drill BDP_03 to test the basal contact of the lower ultramafic unit immediately below DRAC35 as well as an eastern extension of the mineralisation encountered in DRAC35 and DH1, which will test a strong DHEM anomaly identified in drill hole DDD002.
Analysis
It is still early days, but the preliminary observations of the first hole at Desert Dragon Central are encouraging with the results indicating the ultramafic channel is fertile for massive nickel sulphides.
News flow will remain strong in coming weeks and months, with preliminary results and then assays to flow through.
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