Three years ago, while we just processed the very first till samples with our ARTGoldTM technology, we got the surprise to fid abundant platinum group minerals (PGM) among the gold grain concentrate. Since then, we have learn that PGM are not that rare, and can be recovered from till samples all over Canada regardless if the district is renown or not for its platinum endowment.

PGM are a complex family of minerals including dozenstens of mineral species, involving 9 different precious metal and seven metalloids acting as ligand. These minerals bear in common being relatively dense, variably distinctive, usually stable, but all very small, typically less than 20 microns across. But they might not be that rare... just difficult to recover and count!

Smallness of PGM grains precludes their recovery by conventional heavy mineral methods as used for gold grain counting. Moreover, their variable looks and non-contrasting colour, combined to their small size, make these indiscernible under conventional binocular microscope, regardless of the mineralogist expertise. Using our proprietary fluidized bed recovery technology and automated SEM-based mineral detection circumvented the issue for routine work. Overall, based on the thousands of till samples we processed since inception of ARTGoldTM, PGM were detected in about 20% of samples, regardless of their provenance. This contrasts with conventional technique, which never yielded a single grain in Québec!

Are they that rare? We recently conducted a survey in which we scanned with an SEM a batch of thin sections from basalt of the Hellancourt Formation, Labrador Through. And PGM grains were detected in many of these, in situ, exceedingly small (1-2 microns), in non-mineralized boring rocks, almost devoid of sulfides!

Since 2 years, we are accumulating data from all over eastern Canada. We built a database with 1500 PGM analysis, including high- resolution images and morphologies, from more than 20 mineral known species. Furthermore, we detected about 10 undocumented mineral species, with previously unknown composition. Furthermore, we documented the effect of weathering on their composition, their morphology and association. This will be thde topic of a talk at RFG2018 by Dr. Phillipe Pagé (session Min-38, Monday, June 18, 11:45 am).

Initially considered as a mere curiosity, this is likely the most effective platinoid exploration technique in glaciated terrain.

'‘There are those who follow the rules... and those who define them!

Typical example of platinum group minerals as detected with ARTGoldTM technology in till samples from southern Ontario.