Tin-tantalum pegmatites of the Northern Territory - summary

The following notes are derived from the abstract of Frater M, in prep. Tin-tantalum pegmatites of the Northern Territory. Northern Territory Geological Survey, Report 16.

Tin- and tantalum-bearing pegmatites in the Bynoe area are located in a north-trending, 10 km-wide belt extending from Kings Table to the Finniss River in the Bynoe 1:100k sheet. These occurrences were discovered at the turn of the last century and total recorded production is 533 t of cassiterite concentrate and 63 t of tantalite concentrate.

There are over 150 mineralised pegmatite bodies concentrated in three fields in the Bynoe area. The northern group, centred on Observation Hill, contains the majority of mineralised pegmatites and was investigated by Greenbushes Tin Ltd. The second group is situated along the upper reaches of Leviathan Creek and contains about 30 closely spaced pegmatites. The third group is between Annie River and Gorge Creek and contains about 35 widely spaced pegmatites. Previous mining and exploration of Bynoe pegmatites is restricted to the weathered zone down to 20 m in depth.

Several pegmatites extend to the south of the Bynoe area. One group includes the historic Mount Finniss, Goodwill and Bamboo Creek Mines and is concentrated around the margins of the granite stock straddling the northern boundary of Litchfield National Park. Recently, other tin-tantalum pegmatites have been recognised overlying granite on Labelle and Twins Stations to the west and southwest of the Litchfield stock.

Elsewhere in the Pine Creek Orogen, tin-tantalum pegmatites were mined in the Shoobridge area prior to 1890. During 2001, Julia Corporation sampled a mineralised pegmatite swarm (Two Bobs) located to the south of Shoobridge.

Tin-tantalum pegmatites are also present in the Arunta Region. At Barrow Creek, several Sn (-Ta) pegmatites were mined during the 1950s and others were located during exploration in the 1970s. Lode and alluvial tin was recovered from pegmatites on the Anningie Tin Field during the 1930s. Tantalite was reported but never marketed.

Tantalum-bearing pegmatites also occur in the Elkedra 1:250k sheet at the Utopia and Spotted Wonder Prospects on Mount Skinner and Delmore Downs Stations, respectively. These pegmatites are reported to be bismuth-associated rather than cassiterite-bearing. Small-scale mining of the deposits ceased by 1949. In the west, in the Napperby 1:250k mapsheet, tin-tantalum pegmatites are recognised in granite at Double Dam on Denison Station. Production was largely from alluvial workings.