This report relates to part of a geological prospecting program of reconnaissance rock chip samples collected by Colin Plumridge during the period 1975-79 for North Broken Hill Ltd on the Cobar and Nyngan 250K sheets. The intention of the sampling was to locate mineralisation that had escaped past detection due to such factors as poor rock exposures and the common ferricrete rubble on the surface, making gossan search difficult. The samples were largely of high iron rocks but also included iron with quartz and occasionally straight quartz samples. Very few of the samples are of rock devoid of iron or quartz.

The sampling work located several new prospects and relocated many areas with old pits that had not previously been recorded. Some of this work was included in exploration licence reports; however, the majority of results were never formally reported to the Department. To rectify the situation Colin Plumridge has provided location data for the samples as well as the original assay sheets from the North Broken Hill lab in Moonta SA. As the objective of the sampling was to locate an Elura type deposit, the samples were only assayed for Cu, Pb, Zn, Ni and Ag; very few of the samples were assayed for Au or As.

Contents of this report include:

• Analytical information
• Location map of samples
• Appendix 1: Assays from ALS lab in Brisbane
• Appendix 2: 6390 Rock geochemical samples Cobar-Nyngan 1:250000 sheets
• Appendix 3: Sample location, descriptions and original assays from North Broken Hill lab, Moonta, South Australia