1971 Report on AP 3113 Bonya Plains

Abstract

03/05/1971 to 02/06/1971 - During this period an investigation was made of the sedimentary ranges on the northern boundary of the AP. While this area wasn't considered particularly promising, consisting mainly of limestone beds and siltstone capped with quartzite, we were delighted to discover a very thin horizon of copper near the base of a quartzite. First indications of mineralisation were several plants of a unique species (known locally as copper bush) that will only grow on or near outcropping copper, and indeed this was the case here, though the bed was of about the thickness of a cigarette paper and contained only the most minute amount of Cu in malalmite form. It was noticed that in several vertical joints and other areas of minor disturbance the seam was slightly thicker and one is inclined to wonder if the Cu was carried there in solution after the sediments were layer down rather than as particles put down with the sediments. Along the base of these hills where they contact the metamorphic rocks further odd traces of Cu were found and also some barite in the fault zones, but generally the area is unrewarding. Also an area southwest from Jericho (ML 13614) of a particularly decomposed schist overlayed with alluvium was prospected in detail. This schist has small outcrops of calc-silicate all of which contain scheelite of low grade in small isolated grains. The average grade of these outcrops would not exceed 0.1% (visual estimate by UV lamp) and it is doubtful if they will ever come to be regarded as economic. Two men were employed during the period using one vehicle. Report 2 - During the month ended June 2nd work in the AP was centered in a zone along the south-western boundary of the land near the Marrakesh leases 4, 5 and 6 and Asmara 2. This is an area consisting chiefly of anphibolite schist, with minor outcrops of calc-silicate, skarn and quartz. Mineralisation here appears to be confined to the quartz reefs and includes copper, scheelite and hematite. All in insignificant quantities. While these quartz reefs are of little consequence, several of them have proved to be sources of sheelite, suitable for testing for impurities and assaying. An eight foot shaft has been sunk into one of these and the scheelite recovered was readily concentrated by hand sorting due to it being fist sized lumps in the quuartz, (as opposed to the skarns on the mineral leases where the scheelite is mostly disseminated). To do this work two aboriginal men were employed and their wives helped with the hand sorting. The assay of the sample has proved encouraging for it shows an apparent lack of any impurities of a deleterious nature. Results were 71.1% WO3, no arsenic and only 0.05% tin. Also during the month a mineral was found to the north of Marrakesh during routine prospecting which was forwarded to the Mines Branch Alice Springs. While I'm aware of the occurance of barytes in this general area I thought it prudent to have it checked for strontium, in the possibility of its being celestite. (However it proved to be common or garden barytes). During the month of September an area around two copper propects was prospected and the deposits themselves given a reappraisal. These deposits have been known for some years and contain some fairly high grade ore, but as with all of the outcrops of this mineral on the AP the deposits themselves are small, although traces of Cu can be found over a length of half a mile. During the month of July an area on the eastern boundary was prospected. This area is mainly comprised of sediments and granite, brecciated quartz veins, calcsilicates and pegmatites. This section appears to have little mineralisation apart from a small occurence of manganese and barite discovered in the bank of the creek.