This site is different to 'Brockman' as the central area of the Halls Creek Goldfield. The Brockman REE prospects can be found about 12 kilometres south south-east of Old Halls Creek. From Old Halls Creek is a track which heads south, then south-east, constructed by Martin Yenma early 2000's to access the Ruby Queen Mine. (Source Doug Stone's map...possibly the name above should be Ynema, at least according to official warden court documents).

A track leaves this road and heads north-east, the first prospect found after one kilometre and several more along a 3.5 kilometre line, short distances either side of the track.

Drilled by Hastings Rare Metals Limited. A JORC resource was produced exceeding 22 Mt at 0.795 ZrO2, 0.31% Nb2O5, 0.023% Ta2O5 and 0.10% Y2O3. The deposit is said to contain significant amounts of yttrium and dysprosium.

Major drilling and plant scale testing was conducted at the site by Union Oil Development Corporation in the 1980's. This stated the site contained 45 Mt JORC Indicated and Inferred, consisting of 0.44% Nb2O5 (niobium oxide), 0.027% Ta2O5 (tantalum oxide), 0.124% Y2O3 (yttrium oxide), 1.04% ZrO2 (zirconium dioxide), 0.011% Ga (gallium compounds), 0.035% HfO2 (hafnium oxide) and 0.09% combined rare earth oxides.

The rare earths are hosted by fluorine bearing tuffaceous rhyolitic volcaniclastics of the Brockman Volcanics, locally called the 'Niobium Tuff', also described as trachytic ash flow tuff. The deposit is 5 to 35 metres wide , 3.5 kilometres long, north-east trending, steep to vertical dipping, within a mafic to bimodal metavolcanic and metasedimentary greenstone. Associated rocks are trachytic flows, agglomerates, sub-volcanic intrusives, and lahars (ancient volcanic mudflows).

The rocks were deposited as part of a small shield complex eruption, probably in a rift related basin, in a shallow marine setting. It is located in the Halls Creek greenstone belt, the deposits showing extremely fine-grained zircon, columbite, Y-niobates, minor bertrandite, bastnasite, parisite, in an altered trachytic ashflow tuff.

The sources state the mineralisation was formed by syngenetic with modification by Fe-rich solutions soon after deposition, or synorogenic alkaline metasomatism.

Other Regions, Features and Areas containing this locality

References