Aston Minerals’ petrographic analysis confirms nickel sulphide affinity at Boomerang target
Aston managing director Dale Ginn says the nickel sulphide minerals at Edleston are commonly recovered from major nickel operations including BHP’s Mt Keith and Yakabindie mines.
Initial petrographic analysis of drill core samples from Aston Minerals’ (ASX: ASO) Boomerang nickel-cobalt target within the Edleston project in Canada has confirmed sulphide affinity with respect to nickel mineralisation.
Seven samples representing a broad spectrum of grades encountered from drilling to date were macroscopically examined and thin polished sections taken from representative zones of mineralogical and textural interest.
All sections were then examined with a petrographic microscope in transmitted and reflected light, and interactive scanning electron microscope (SEM) work was completed to identify very fine-grained phases and confirm observations.
Aston said partial digest versus total digest methods demonstrated 93% liberation of nickel across all drill holes to date, confirming the nickel is associated with sulphides.
Nickel sulphide assemblage includes pentlandite-millerite-heazlewoodite, with estimated nickel tenor from scanning electron microprobe ranging from 8.4% to 62%.
The analysis has provided further context to strong assays received to date and increased Aston’s confidence that the mineralisation is associated with conventional sulphide species, which are highly amenable to extraction.
Definitive confirmation
Aston managing director Dale Ginn said the analysis provided a definitive confirmation of the species of nickel sulphide present at Edleston.
“The nickel sulphide minerals identified at Edleston are commonly processed and recovered from multiple nickel operations including Mt Keith and Yakabindie (owned by BHP, ASX: BHP),” he said.
“Of particular note is the lack of nickel alloy minerals, arsenopyrite and other arsenic bearing minerals at the Bardwell prospect, which correlates with an earlier nickel liberation analysis demonstrating that between 96% and 100% of nickel was liberated at Bardwell.”
Mr Ginn said a 30kg sample of mineralisation had been submitted for initial metallurgical testing to confirm a broader distribution of nickel sulphide species, in-situ grain size analysis and conventional flotation testing.
Greenstone belt location
The Edleston project is located within Ontario’s Abitibi greenstone belt of Archean metavolcanic and medisedimentary units that have been steeply folded with axes trending in general east-west orientation.
The Boomerang target is interpreted to be a dunite-peridotite unit spanning over 6.5km of strike which has undergone extensive serpentinisation.
This process is responsible for the reaction of olivine to produce magnetite and brucite, resulting in a strongly reducing environment whereby nickel is released from the decomposition of olivine.
The nickel which has been released is typically partitioned into low sulphur nickel sulphide minerals.
Due to the magnetite association with mineralisation, Aston has generated a 3D inversion model of magnetics to assist with exploration targeting.