Covering a combined land area of 259 km2, the Sandstone Project (Gidgee North and Gidgee South) is centrally located between the towns of Sandstone to the south, Meekatharra to the northwest and Wiluna to the northeast.
The Gidgee North project lies adjacent (approx. 10 km) to the Horizon Gold Ltd owned Gum Creek Project.
Gum Creek has historical production of >1Moz of gold and Horizon’s Gum Creek project currently hosts JORC 2012 Resources of 15.9 Mt @ an average of 2.7 g/t Au for 1.39 Moz Au (Horizon Gold Ltd ASX announcement 12 July 2019)
The Sandstone Project comprises extensions to structures that host mineralisation at the Gum Creek Project with their prospectivity demonstrated by the presence of historical workings and gold-in-soil anomalies.
Very limited modern exploration and drilling along the Gum Creek greenstone belt and along strike from known gold mines.
The tenement package provides opportunities for large-scale discoveries within the Gidgee Shear Zone.
Gidgee North & Gidgee South
The Sandstone Project provides opportunities for the discovery of the various mineralisation styles with the Gidgee Shear Zone extending through the southern tenement and the presence of banded iron formation on the northern tenement. Five main styles of mineralisation have been exploited in the Gum Creek Greenstone Belt
(Horizon Gold, 2016)
• Quartz-carbonate (±pyrite, arsenopyrite, galena & sphalerite) veins. Typically free-milling and locally high grade (>20g/t Au). Form complex conjugate vein arrays associated with brittle dilational openings developed along major shears within competent mafic host rocks. Carbonate-sulphide wall-rock alteration is common about mineralised zones and extensive supergene enrichment often overlies the primary mineralisation zones. Deposits of this type represent the dominant mineralisation type at Gum Creek and include Swan Bitter, Swift, Kingfisher and Wyooda/Thangoo.
• Ductile shear hosted mineralisation – arsenopyrite dominant. Fine grained gold associated with sulphide rich, intense biotite-sericite altered narrow ductile shear zones. Gold grades are typically in the range 5-10g/t Au. Arsenopyrite and pyrrhotite are the dominant sulphides with most gold locked within the arsenopyrite. Examples of this style of mineralisation are the refractory deposits of Wilsons, Heron South, Snook and Camel Bore.
• Ductile shear hosted mineralisation – pyrite dominant. Fine grained gold associated with sulphide poor, broad ductile shear zones developed within mafic host rocks. Shearing typically defined by weak biotite alteration, up to 1% fine pyrite and a sparse network of thin (1-3mm thick) quartz veins. Gold grades are typically in the range 0.5–1.5g/t Au and the mineralisation is free milling. The Howards deposit is representative of this mineralisation style.
• BIF hosted mineralisation. Quartz-pyrrhotite veining and pyrrhotite replacement of magnetite meso-bands form narrow steep-plunging shoots of limited length and width, but extending to depth. This mineralisation style occurs in fold hinges within banded iron formation marginal to major north-south shear zones, and is similar to the Hill 50 mineralisation at Mt Magnet. Grades are typically 1-10g/t Au and the mineralisation is free milling. The Omega deposit is of this style.
• Quartz veins. Sulphide poor, sheeted and anastomosing quartz veins and lenses developed in shears straddling granodiorite contacts within the Gum Creek Greenstone Belt. Grades are typically 1-5g/t Au. The Montague deposits, which are free milling, represent this style of mineralisation.