Merlin Project

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Mine TypeOpen Pit
StagePreliminary Economic Assessment
  • Diamond
Mining Method
  • Truck & Shovel / Loader
Mine Life... Lock
SnapshotWork continued on the Merlin Project Feasibility Study during the third quarter of 2023. Completion of the Study has been delayed while the team investigates lower capital and lower plant throughput options considering the current capital market conditions.


Lucapa Diamond Company Ltd. 100 % Indirect
In May 2021, Lucapa executed binding agreements to acquire 100% of the historic Merlin Diamond Project in the Northern Territory of Australia. As per the ASX announcement on 13 December 2021, the formal acquisition process has been completed and Lucapa has, through its wholly owned subsidiary, Australian Natural Diamonds Pty Ltd, acquired 100% of Merlin.



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Deposit type

  • Kimberlite


The Merlin kimberlite field is situated on the eastern side of the North Australian Craton, ~100km south-west of the coast of the Gulf of Carpentaria. The Merlin kimberlites are Devonian in age (382 million to 352 million years ago) and intrude mid-Proterozoic shales and dolomites of the McArthur Group and the unconformably overlying Cambrian Bukalara Sandstone. Thin deposits of Cretaceous sediments and laterite overlie the pipes.

The Merlin pipes are small, with the diameter of the upper levels varying between 50m–125m. At surface the shapes of the pipes are circular to elliptical and maintain their regular shape and near vertical sides within the Bukalara sandstone. In the softer sediments beneath the Bukalara/ Proterozoic unconformity, some pipes increase in diameter. In the case of Palomides and Sacramore they coalesce into a larger single vent named PalSac.

The kimberlites are strongly weathered to 60m - 80m depth from surface and appear to have sunk back down into the craters, that have been in-filled with Cretaceous sediments that are up to 40m thick. The sagged nature of the infill sediments, the upturned edges with associated slickensides, the presence of a basal non-kimberlitic conglomerate and the thickened iron pisolite profiles, all suggest that the Cretaceous aged sediments have subsided into the pipe structures possibly due to solution weathering of the kimberlite.

The pipes are located within four main clusters over an area of 10km by 5km and are located close to the projected trace of the north-west trending Merlin Fault, which appears to have had a strong influence on the intrusion of the kimberlite volcanoes. The most northerly Emu cluster, consisting of two pipes (on the exploration licence), lies outside the current mineral lease and from the limited sampling data available are currently not known to be economic.

The remaining 11 pipes (contained in three clusters) are all significantly diamondiferous and are situated within the mining lease. They are named Bedevere, Kaye, Ector, Gareth, Ywain, Gawain, Tristram, PalSac, Excalibur, Launfal, and Perceval.

Five broad categories of kimberlite facies have been recognised: these being epiclastic kimberlite, tuffisitic kimberlite, tuffisitic kimberlite breccia, pelletal tuffisitic kimberlite and micaceous tuffisitic kimberlite. The presence of epiclastic kimberlite in the Emu 1 pipe and in Gawain, indicate the pipes are preserved at the upper diatreme level. The Crater facies evident at Merlin would have been present subsequent to emplacement buthave since been eroded and only the diatreme facies are currently evident.



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Mining Methods


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Crushers and Mills


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CommodityUnitsAvg. AnnualLOM
All production numbers are expressed as mineral.

Operational metrics

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Stripping / waste ratio  ....  Subscribe
Waste tonnes, LOM  ....  Subscribe
Ore tonnes mined, LOM  ....  Subscribe
Total tonnes mined, LOM  ....  Subscribe
Tonnes processed, LOM  ....  Subscribe
* According to 2022 study.

Production Costs

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Assumed price Diamond AUD  ....  Subscribe
* According to 2022 study / presentation.

Operating Costs

OP mining costs ($/t milled) AUD 31 *  
Processing costs ($/t milled) AUD  ....  Subscribe
G&A ($/t milled) AUD  ....  Subscribe
Total operating costs ($/t milled) AUD  ....  Subscribe
* According to 2022 study.

Project Costs

MetricsUnitsLOM Total
Initial CapEx $M AUD  ......  Subscribe
Total CapEx $M AUD  ......  Subscribe
OP OpEx $M AUD  ......  Subscribe
Processing OpEx $M AUD 172
Total OpEx $M AUD  ......  Subscribe
Gross revenue (LOM) $M AUD  ......  Subscribe
EBITDA (LOM) $M AUD  ......  Subscribe
Pre-tax Cash Flow (LOM) $M AUD  ......  Subscribe
Pre-tax NPV @ 7% $M AUD  ......  Subscribe
After-tax NPV @ 7% $M AUD  ......  Subscribe
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Pre-tax payback period, years  ......  Subscribe

Heavy Mobile Equipment


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Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jan 18, 2023
....................... Subscription required ....................... Subscription required Subscription required Oct 6, 2023
....................... Subscription required ....................... Subscription required Subscription required Jan 18, 2023

Total WorkforceYear
...... Subscription required 2022

Aerial view:


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