Dart Mining (ASX:DTM) reports assay results from four rock chip samples collected at the historical Walwa tin mine in north-east Victoria, with the ‘highest-grade’ sample returning 3.96% tin.
The samples were collected in June from the historical Walwa open pit and the Mt Alwa South prospect.
Sample WWP002, an in-situ grab sample of cassiterite-bearing pegmatite from the south-west wall of the historica; pit, returned 3.96% tin (Sn), 165 parts per million (ppm) tantalum (Ta), and 197ppm niobium.
Three other samples returned between 0.40% and 1.09% Sn. All four samples showed elevated lithium, rubidium, and caesium levels, consistent with a fractionated, tin-tantalum specialised pegmatite system.
Chairman James Chirnside says the results provide confidence ahead of the planned deep drilling program.
“Almost 4% tin in a rock sample taken from the wall of the old Walwa pit sits alongside decades of historical sampling that tells the same story — that the Walwa dykes are rich in tin, and associated tantalum and niobium,” Chirnside says.
“This gives Dart Mining confidence as we finalise the deep drilling program designed to test for a larger tin-bearing greisen system beneath the historic workings.”
Historical sampling supports the new results, with previous explorers reporting up to 2.91% Sn at Mt Alwa South, 0.39% Sn at the Walwa pit, and 0.44% Sn with up to 670ppm Ta at Snake Gully.
Walwa has the ‘highest recorded primary tin production’ in Victoria, with about 97,000 tonnes of ore treated from the open pit when it was last mined in the late 1960s.
The tin-bearing dykes are 1–8m thick and dip at 20–30° to the northwest, north, or northeast, forming a broad dome plunging northward. They are predominantly aplite with pegmatite and greisen phases, and commonly contain coarse cassiterite along their margins.
Dart has compiled 150 historical drill holes at Walwa and reported pre-JORC historical estimates by Union Corporation of 8.64 million tonnes at 0.163% Sn and 50ppm tantalum oxide.
These estimates are not reported in accordance with the JORC Code (2012) and are not being treated as current mineral resources.
Dart Mining plans to commence maiden diamond drilling at Walwa in October, with preparations under way across nine proposed drill sites.
Drilling will target repeated tin-mineralised dykes at depth and a possible tin-rich greisen zone at the top of the interpreted causative intrusion.
Write to JC Villarba at Mining.com.au
Images: Dart Mining
