Annual report on EL 2197 Douglas River

Abstract

Following the seasonal drying out of the low swampy granite areas between Emerald Springs roadhouse and the prospect area, I took G. Orridge to the area. G. Orridge was retained by Greenex to evaluate the mineral potential of the general area, with particular emphasis on the potential for further repetitions of Porters Lode style Copper, Cobalt, Nickel sulphides. Mainly due to the absence of precious metal 'sweeteners' in the known mineralization and their limited size, he concluded that further expenditure searching for repetitions of Porters Lode was not warranted. A copy of G. Orridge's report to Greenex is enclosed. The alluvial tin deposits of the Douglas River have been known since the 1890's, however they have never been evaluated in a modern and systematic manner. The whole area of Cullen granite on the license area was found to contain traces of cassiterite and ilmenite. During July 1 981, 4 days were spent panning the gullys and slopes of the north east corner of the license. The average grade observed was about 0.15 kg/m3. A composite sample was submitted to the Greenbushes Tin Ltd laboratory and it confirmed the tin values and also disclosed the presence of minor tantalite. At present the exact nature of the tantalite occurrence is not known and would require a much larger volume of concentrate to determine whether the tantalum and niobium occur as normal tantalite or locked as composite particles with either the ilmenite or the cassiterite. The cassiterite is typical 'granite' type, very fine, black, amber and ruby. Tantalite occurs in every other place I have seen in the Northern Territory and Western Australia only with black cassiterite, so its presence is a real surprise. Subsequent assays have confirmed tantalum and niobium on adjoining Exploration License 2107. At the end of August 1981 the northern tributaries of the Douglas River were sampled (as per sample location map). Although some heavy minerals were present there is no reason to believe the recently eroded overlying cretaceous has formed economic concentrations of tin, tantalum and niobium in the drainages incised into the upper Proterozoic sandstones. As the topography is quite rugged in the sandstone belt, only major drainages were sampled. Difficulty in locating suitable sample points for lead, copper, zinc targets resulted in no samples being taken. Most of the streams are in fact paper bark swamps so we now know that the appropriate sampling method will be hand auger holes bored as deep as is practicable. All samples taken for tin, tantalum and niobium were examined for diamonds and diamond indicator minerals, with negative results. No evidence was found of outcropping base metal mineralization in the small area of Cullen granite that falls within the Exploration License boundary.