Lithium Bearing (LCT) Pegmatites
Dart Mining utilised it’s own extensive knowledgebase built up around the regional geological setting of NE Victoria to initiate a new Lithium Strategy. Two strategic exploration licence applications covering approximately 460 km2 (EL006277 – Empress & EL006300 – Eskdale) add to an existing tenement held along the Dorchap Dyke Swarm (see Map below). The Dyke Swarm is prospective for Li, Sn and Ta hosted by pegmatite dykes. The pegmatite dykes persist for over 50km from south of Glen Wills to north of Eskdale and have been subject to historical tin mining but no previous lithium exploration. Dart Mining has confirmed the Lithium, Cesium, Tantalum (LCT) nature of the Dorchap Dyke Swarm and has shown that highly anomalous levels of Li, Ta, Cs, Rb and Nb are present in at least the Blue Jacket Pegmatite. Dart Mining therefore has the opportunity to undertake the first exploration for lithium in this newly identified province and are planning exploration programs across EL5315 and license applications EL006277 / EL006300 upon granting.
LCT complex pegmatites develop above and adjacent to fractionated granites where favourable pegmatite chemistry has caused significant enrichment of elements such as Sn, Ta and Li. A concealed ridge of granite has been proposed (Whitelaw et al., 1915) between the Mt Wills Granite and the Yabba Granite (Dorchap Dyke Swarm – see Map above), acting as a potential source of Li, Sn and Ta in the dykes of the belt. Limited work by the Geological Survey of Victoria (Maher & Morand, 2003) suggests the dyke chemistry indicates an exotic source for the mineralised pegmatites from a concealed granite source rock. Limited assay data of tin mineralised dykes in the Mitta Mitta area from this work shows elevated Li, Ta, Cs and Rb consistent with the LCT Pegmatite class. The Glen Wills tin field was discovered in 1887 and the Eskdale – Mitta Mitta field followed in 1891 but both were abandoned following the discovery of gold in the same areas by 1895. A brief revival of tin prospecting in the dykes occurred in 1911 defining 100 mineralised pegmatites near Mitta. The Geological Survey of Victoria mapped a total of 1480 dykes and 73 reefs (Whitelaw et al., 1915) with an additional 367 dykes and 36 reefs mapped by Cuffley (1978) in the Eskdale – Mitta area which were outside the area of the Whitelaw et al., (1915) mapping. Regardless of the source, the belt has been described as “virtually saturated with pegmatite dykes” – (Essex Minerals, 1978), the recent confirmation of lithium mineralisation supports the proposed exploration in this newly recognised region that remains unexplored for lithium.