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Australia

Merlin Project

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Overview

Mine TypeOpen Pit
StagePermitting
Commodities
  • Diamond
Mining Method
  • Truck & Shovel / Loader
  • Dredging
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SnapshotThe Merlin is a past-produced mine. Eight of the 11 known kimberlite pipes at Merlin were mined between 1999 and 2003. Lucapa will investigate and seek to utilise existing infrastructure for re-start plan for Merlin.

In November 2023, Lucapa announced that the large scale Merlin Feasibility Study was on pause in favour of advancing an alternative study which focuses on a smaller scale, lower cost pathway to development.

On 25 November 2024, Lucapa released details of its plan to re-start production at Merlin Diamond Mine. The new plan comprises two phases. Phase 1 will use excavator dredging from the base of five existing open pits. Phase 2 will use Vertical Pit Mining to extract ore from the Gawain pit.

A Mining Management Plan application was submitted to the NT Department of Industry, Tourism and Trade in Q2/2024 for the Vertical Pit Mining of Gawain.

Owners

SourceSource
CompanyInterestOwnership
Lucapa Diamond Company Ltd. 100 % Indirect
The Merlin Diamond Project is 100% owned by Lucapa Diamond Company Ltd. through its subsidiary Australian Natural Diamonds Pty Ltd.

Contractors

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Deposit type

  • Kimberlite

Summary:

The Merlin diamond project comprises 13 kimberlite pipes arranged in 3 clusters and extending over an area of approximately 8km x 2 km. Kimberlites are ancient explosive volcanoes which are sourced at depths of 150 to 450km in the earth and bring diamonds from those depths to the surface during eruptions. The Merlin kimberlite pipes are relatively small, ranging from 20 to 250m in diameter but contain good grades of high quality diamonds and while generally slightly funnel shaped, largely maintain their cross-sectional area with depth. The Palomides and Sacramore pipes coalesce at around 120 m below surface to form the PalSac pipe.

The pipes are estimated to have erupted approximately 380 million years ago (ma), through the Cambrian Bukkalara sandstone formation which overlies the Proterozoic McArthur group sediments deposited between 1800 and 1575 ma.

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.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityUnitsAvg. AnnualLOM
Diamond carats 113,530314,000
All production numbers are expressed as mineral.

Operational metrics

Metrics
Hourly processing capacity  ....  Subscribe
Annual processing capacity  ....  Subscribe
Tonnes processed  ....  Subscribe
Ore tonnes mined, LOM  ....  Subscribe
* According to 2024 study.

Production Costs

CommodityUnitsAverage
Assumed price Diamond AUD  ....  Subscribe
* According to 2024 study / presentation.

Operating Costs

CurrencyAverage
Processing costs ($/t milled) AUD  ....  Subscribe
G&A ($/t milled) AUD  ....  Subscribe
* According to 2024 study.

Project Costs

MetricsUnitsLOM Total
Initial CapEx $M AUD  ......  Subscribe
Gross revenue (LOM) $M AUD  ......  Subscribe
Pre-tax Cash Flow (LOM) $M AUD  ......  Subscribe
Pre-tax NPV @ 10% $M AUD  ......  Subscribe
Pre-tax IRR, %  ......  Subscribe

Required Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Nov 26, 2024
....................... Subscription required ....................... Subscription required Subscription required Nov 26, 2024
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Aerial view:

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