The pair, which have long considered Mt Thirsty as an undervalued cobalt project, took a fresh look at the geology when Galileo announced its nickel-copper-platinum group element find earlier this year.
They quickly realised they had similar prospectivity near the contact between the ultramafic rocks of the Mount Thirsty Sill complex and the underlying Mount Kirk Formation sedimentary unit, some 400m south of Callisto.
An expedited drilling campaign was quickly rolled out.
It delivered immediate encouragement with 65m of disseminated sulphides from 190m last month, and today it revealed four more diamond and RC holes have delivered intercepts with sulphides over 52-127m in thickness from depths as shallow as 178m.
Heavily disseminated sulphides were logged over thicknesses between 19-72m.
The logging has noted indications of copper and nickel in chalcopyrite, pentlandite and pyrrhotite, which is encouraging given they are associated with PGE mineralisation at Callisto.
The hope is the drilling, close to the permit boundary, will uncover an extension from the discovery in the north.
The Mt Thirsty partners say they have defined a prospective exploration horizon of at least 300m by 400m, with the target open in all directions, and dipping to the south for about 2km of strike.
Greenstone managing director Chris Hansen said the early indications were impressive given the thick and continuous zones of mineralisation.
Up to 15 more holes for 4200m are planned over the next 6-8 weeks, shifting to the south and east, and plans are already being developed for a second 14,350m campaign, pending the assay results.
The assays are expected to flow through within weeks. The core will be assayed for a range of metals, including palladium, platinum, gold, copper, nickel and rhodium.
Mt Thirsty is 16km from Norseman, Western Australia, at the southern end of the Norseman-Wiluna greenstone belt.
Callisto is just 200m into Galileo's tenure and has some similarities in mineralisation style to the massive Platreef deposits on the northern limb of the Bushveld Complex in South Africa.
Despite extensive shallow drilling, largely targeting the 26.9 million tonnes at 0.125% cobalt and 0.54% nickel Mt Thirsty resource area, the joint venture area remains largely untested, and only a fraction of 7000 holes completed finished below 100m.
Few holes were sampled for PGEs, and most of the core and pulps have been destroyed.
The area also has potential for lithium-bearing pegmatites.
Conico had cash of A$1.9 million at the start of the quarter to fund Mt Thirsty and its holdings in Greenland, while Greenstone has around $6 million cash.
Greenstone shares were up 12% this afternoon to 7.5c, valuing it at $79 million, while Conico's stock was up 7% at 5.9c, capitalising it at $86 million.
