The Rosetta Royalty covers the Conway and Bimurra Projects which are epithermal gold targets within the Drummond Basin. The Drummond Basin has been a major gold producer since the recognition of the significance of epithermal mineralising systems led to the discovery of a number of gold deposits in the area in the 1980’s including Wirralie, Pajingo and Yandan. A gold endowment in excess of 7 million ounces has been identified in the Drummond Basin to date.
The Bimurra Prospect represents a large mineralising hydrothermal system (The Bimurra Hydrothermal System) hosting numerous prospects and mineral occurrences, almost all fit into the styles generally associated with epithermal low sulphidation mineralising systems. Previous explorers have identified and named nine gold prospects; Blenheim, Hilltop, Perseverance, Elizabeth, Bimurra East, Camp Creek, Ramillies, Bungobine Peak and Bimurra North East. In addition, a number of conceptual targets have been identified based on structural interpretation, soil and rock chip geochemistry. The area is also dotted with occasional unnamed pits and shafts from previous prospecting activity.
Initial interpretation and modelling is now well advanced for the main Bimurra mineral occurrence, which includes the Perseverance and Elizabeth zones, the two most intensely tested areas by previous explorers. Detailed mapping has identified numerous continuous and semicontinuous zones of chalcedonic quartz veining, stockwork and brecciation. Rock sampling and drill testing, both diamond and reverse circulation percussion, has confirmed that gold mineralisation continues to depth and over significant strike lengths.
Exploration Target for the Bimurra Prospect
Previous exploration results for the area historically referred to as the Bimurra Prospect (including the Perseverance Lode and part of the Elizabeth Breccia) have been compiled and a preliminary three dimensional model created encompassing a series of broad zones of gold mineralisation and associated quartz veining. This model was created to allow the near surface potential (maximum depth of model is 180 metres below surface) of the area to be evaluated as an exploration target.
GBM previously estimated an exploration target range for the Bimurra mineralisation of between 10Mt at an average grade of 0.7 g/t Au containing an estimated 230,000 ounces of gold and 4Mt at an average grade of 1.2 g/t Au containing an estimated 120,000 ounces of gold. It should be noted that the potential quantity and grade is conceptual in nature, there has been insufficient exploration to estimate a Mineral Resource and it is uncertain if further exploration will result in the estimation of a Mineral Resource. It should be emphasised that this target estimate does not consider the potential for bonanza grade veins or shoots to exist in the Bimurra Prospect either near surface, or at depth.
The Conway Project
The Conway Project contains multiple prospects and is considered to hold potential for both bonanza epithermal vein style deposits and bulk tonnage low-grade disseminated gold deposits. The Conway Project includes a number of defined prospects; Wobegong, Red Flag Hill, Quartz Reef Hill, Split Hill, Bustard Egg Hill, Mill Hill, Big Sinter Hill and Silica Valley. Mineralisation is largely controlled by a broad northeast trending dextral shear system with the majority of outcropping mineralised quartz veins lying along these trends. The highest grade rock chip samples and drill intersections have come from multiphase brecciated type veins, the best examples of which come from the Wobegong prospect. High-grade drilling results have been intersected by multiple phases of drilling occurring within the Conway area. The highest grade intersects occur within the Wobegong prospect and include 14 m @ 16.08 g/t Au from surface in CFS005 (including 1 m @ 208 g/t Au from 1 m), 2 m @ 26.6 g/t Au from 40 m in CON006 and 8 m @ 4.91 g/t Au from 26 m in C013. Significant results have also been intercepted within the Red Flag Hill prospect including 4 m @ 7.35 g/t Au from 28 m in DDHC081 and 6 m @ 4.13 g/t Au from 26 m in DDHC082 at Red Flag Hill. Other less explored prospects have encountered intercepts which includes 4 m @ 2.56 g/t Au from 224 m in CON018 at Mill Hill, 4 m @ 2.03 g/t Au from 22 m in C035 at Quartz Reef Hill and 10 m @ 0.5 g/t Au from surface in DDHC003 at Bustard Egg Hill.
Previous tenement holders have predominantly tested for shallow mineralisation, leaving significant potential for the discovery of bonanza-style epithermal mineralisation at depth. Mapping and sampling of geochemically anomalous areas has identified extensive areas of silica alteration and high tenor gold results in rock samples. Rock sampling in 2002 within the Wobegong prospect identified two separate high-grade banded epithermal quartz sub-crop samples reporting 422 ppm Au and 360 ppm Ag (sample R/85/R) and 35.1 ppm Au and 13.5 ppm Ag (sample R/98/R).