The Sorpresa Gold and Silver Deposit was a greenfields exploration discovery by Rimfire in 2010, and is 100% owned (this may change with an earn-in joint venture that now operates with New Gold Inc. of Canada). The deposit is comprised of 6 structurally controlled, folded and plunging Gold and Silver rich pods over a curvilinear strike length of 1.7km. Mineralisation is present at surface and at its deepest point has been defined down dip to approximately 500m, which is 150m to 200 metres below surface, where it remains open in multiple directions.
The deposit has been defined with 323 drill holes for 28,898m and is a mixture of high grade oxide and primary mineralisation. A maiden JORC 2012 Compliant Mineral Resource Estimate was delivered in Dec 2014 comprising an Inferred and Indicated Resource of 6.4Mt for 7.9Moz of silver and 125kOz of gold (at 0.5g/t Au & 25g/t Ag cutoff).
The Gold dominant portion of the Sorpresa system represents 3.0Mt @ 1.06g/t Au and 22g/t Ag for 103kOz Gold and 2.1MOz Silver (at 0.5g/t Au cutoff), with the Silver dominant portion representing 3.4Mt @ 54g/t Ag and 0.20g/t Au for 5.8MOz of silver and 22kOz Gold (at a 25g/t Ag cutoff).
Sorpresa is currently interpreted to represent a Carbonate Base Metal Epithermal Au/Ag Deposit, possibly related to Siluro-Devonian volcanism akin to the Mineral Hill and Mt Boppy deposits.
Mineralisation is confined to a variably east dipping, gently folded, variably plunging mineralized plane comprised of silicified / sericite / muscovite / carbonate / pyrite altered, crackle brecciated and carbonate-sulphide-gold cemented, quartz veined meta-siltstone. Sulphide mineralisation hosting gold and silver comprise:
Pyrite = arsenopyrite > sphalerite > galena >> tennantite – tetrahedrite > chalcopyrite and majority as native gold.
Mineralisation is best developed below a quartz-feldspar porphyritic sill complex, itself gently folded, and strongly altered.
The Gold at Sorpresa occurs as Native free Gold formed as ~2 – 50um grains, moderately high fineness (i.e. Au > Ag). Gold occurs as inclusions in Sphalerite with some in Pyrite and Galena. Silver mineralisation occurs in Galena and Tennantite – Tedrahedrite. The Mineralisation has a low temperature of formation indicating an Epithermal setting.
Potential for resource extensions and additional high grade oxide satellite extensions remains high and active exploration programs are in progress.