Dart Mining NL (ASX:DTM) has found spodumene is the primary lithium mineral within the lithium-caesium-tantalum (LCT) dykes at the Dorchap Lithium Project in Victoria.
Some of the best assays from the company’s sampling and analysis program include:
- 10 metres at 14.5% spodumene (Scrubby Creek dyke);
- 10 metres at 8.6% spodumene (Eagle dyke);
- 10 metres at 9.6% spodumene (Eagle dyke);
- 10 metres at 24.3% petalite and 2.9% spodumene (Holloway dyke);
- 5 metres at 22.9% petalite and 3.9% spodumene (Holloway dyke);
- 4 metres at 7.6% petalite and 7.7% spodumene (Holloway dyke);
- 4.8 metres at 10.6% spodumene (Gosport dyke);
- 4 metres at 13.5% spodumene (Gosport dyke); and
- 7 metres at 7.1% spodumene (North Gosport dyke).
Dart chairman James Chirnside said: “Confirmation of spodumene as the primary mineralisation style, with subsidiary petalite in pegmatites, further underscores the importance of Dart’s Dorchap Lithium Project.
“These latest XRD analyses across the project demonstrate the effectiveness of geochemical mapping for pinpointing the main target area for lithium prospectivity.”
The results are in
Dart used X-Ray analysis to investigate 74 samples from the Dorchap Project and uncovered four types of lithium-bearing minerals: spodumene, petalite, amblygonite and cookeite.
The investigation found that spodumene and petalite (particularly spodumene) are the main sources of hard-rock lithium ores.
Studies also show that cookeite is a secondary lithium-silicate mineral formed through the alteration of other lithium-bearing minerals.
Dart selected samples to undergo X-Ray diffraction (XRD) analysis if they had more than 0.2% lithium content.
The pegmatites sampled are primary comprised of quartz, feldspar and mica, with lithium mineralisation spread across the four minerals above.
Of the 74 samples submitted, 58% of the samples demonstrated spodumene mineralisation, 31% demonstrated petalite (11% of samples contain both spodumene and petalite), and 12% contained amblygonite.
Cookeite was present in 55% of the samples analysed, typically in samples containing spodumene.
Lepidolite wasn’t detected using the XRD technique, however, it can be spotted in hand specimens and is locally abundant in some dykes in the Glen Wills area.
What’s more, all of the samples that returned notable concentrations of spodumene and petalite lie within the 20-kilometre by 12-kilometre fractionation zone identified through geochemical trends by Dart Mining geologists.
Dart believes this further indicates it’s honed in on the primary zone of mineralisation at Dorchap.
Digging into Dorchap
Dart Mining geologists first identified the lithium prospectivity of pegmatite dykes in the Dorchap Range in 2016 and set about acquiring exploration leases across the region.
These are the first recorded lithium pegmatites identified in Victoria and are believed to have been sourced from the nearby Mount Wills Granite.
A regional sampling program, consisting of 826 samples, identified a strong fractionation trend across the Dorchap Range.
This lead Dart to what it believes is the primary mineralised pegmatite zone, which bears enriched lithium, caesium, tantalum, beryllium and tin mineralisation.
Dart Mining’s chip sampling program has also seen some promising results, including 16 metres at more than 530 parts per million (ppm) caesium oxide, 0.32% lithium oxide and 104 ppm tantalum pentoxide.
The program also fielded grab samples at 1.57% lithium oxide and 0.1% ppm tantalum pentoxide at the Bluejacket Dyke in Glen Wills, along with:
- 10 metres at 0.95% lithium oxide from the Eagle Dyke;
- 10 metres at 1.38% lithium oxide from the Holloway Dyke (Dorchap Range);
- 10 metres at 1.22% lithium oxide from Scrubby Dyke;
- 1 metre at 838 ppm caesium oxide and 0.46% tin oxide; and
- a grab sample at 9.98% tin oxide from elsewhere in the Dorchap Range.
An initial, short drilling program in 2019 was followed with an airborne LiDAR mapping program in early 2021, which has allowed Dart to map previously overlooked pegmatite dykes in better detail.
