A block comprising 319 square km or ~12.7% of the north-western corner of EL 5223 has been relinquished due to its now perceived diminished prospectivity for containing economic heavy mineral sands mineralisation, due to the apparent general absence there of the target Loxton-Parilla Sands. During this block's tenure by Murray Zircon, the latest company to explore there, 8 vertical open aircore holes for a total penetration of 222 m were drilled in April 2013 along part of a regional drill traverse crossing its northern portion. The holes intersected Bungunnia Limestone, Blanchetown Clay and Norwest Bend Formation sediments, and probably ended within the Murray Group Limestone. No significant heavy minerals were encountered. The drillholes were wireline geophysically logged with a gamma ray tool to obtain information useful for determining the position of the base of any strandlines. Logging of these MXZ-prefix holes identified some suspected pale bentonitic clay occurring over the 1-metre sample depth interval 26-27 m in hole MZX2260. A sample of the clay soil/sediment material was provided to DMITRE, who had an XRD scan, a petrographic thin section examination and a lime sediment silicate analysis done on it for determining the mineral species present. It was found to be a very fine grained dolomite, existing in the form of spherules of <300 microns diameter. Inspection of the logs for surrounding drillholes suggested that there could be a 1 km wide zone containing this dolomite, that may possibly be up to 5.75 m thick in places, e.g near hole MZX2256. With respect to work done by previous licensees on the now relinquished ground portion, this consisted of exploratory aircore drilling also searching for economic heavy mineral sands. In late 1987, Aberfoyle Resources Ltd completed a single drill traverse, MC06, in the eastern part of the relinquished area on their earlier-held tenement EL 1401 Mercunda [these drillhole data, per se, are reported separately in open file Envelopes 6869 and 6870]. Between October 1997 and October 2002, Australian Zircon NL completed 17 vertical holes for 511 m in the southern part of the relinquished area, and the data for these holes are appended herein. Only trace amounts of heavy minerals were revealed, occurring as thin lenses formed within reworked dunal sands, with best results of 1.7% to 1.8% HM recorded from 17-21 m depth in adjacent holes AAMT 7401, 7402 and 7403.