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Australia

Hillgrove Mine

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Overview

Mine TypeOpen Pit & Underground
StageRestarting
Commodities
  • Gold
  • Antimony
Mining Method
  • Truck & Shovel / Loader
  • Avoca
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SnapshotHillgrove Project covers 254km2 and consists of four exploration leases and 48 granted mining leases for 1.7M Resources at 7.4g/t AuEq, placing Hillgrove in the world top 10 global antimony deposits and is Australia’s largest antimony deposit, as well as containing high-grade gold.

Red River (previous owner) started gold production from the Hillgrove mine’s Bakers Creek stockpile in December 2020. The Bakers Creek stockpile was exhausted in Q1 FY22.

On September 7, 2022, Red River placed Hillgrove operation on care and maintenance.

In August 2024, just seven months after the acquisition of Hillgrove was completed , Larvotto released its compelling Hillgrove Antimony and Gold Project Pre-Feasibility Study which outlined robust financials and the near-term antimony and Gold development potential of the project.

Following the delivery of the positive PFS, the Board of Larvotto approved the immediate commencement of the Definitive Feasibility Study.

Owners

SourceSource
CompanyInterestOwnership
Larvotto Resources Ltd. 100 % Indirect
The Hillgrove Gold Project was acquired by Larvotto Resources in December 2023. Larvotto Resources hold 100% interest in all tenement areas.

Contractors

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Deposit type

  • Vein / narrow vein
  • Hydrothermal
  • Breccia pipe / Stockwork

Summary:

Steeply inclined north-northwest, northwest, west-northwest mineralised structures dominate the 10km strike of the Hillgrove mineral field.

The main mineralised structures are composite, occurring as anastomosing sets of fractures, which pinch and swell along-strike. Local dilutional zones host mineralised hydrothermal breccias. The main structures are accompanied by arrays of sub-parallel narrow veins. The northwest striking mineralised structures commonly contain lamprophyre dykes which have been emplaced into mineralised rock and have themselves been variably altered and mineralised.

The mineralisation occurred late in orogenic development and has characteristics of most structurally controlled mesothermal deposits. With metamorphic derived mineralising fluids migrating during uplift and unloading through shear zones to the brittle-ductile transition at which point deposition occurred within high angle faults. Deposition sealed fluid paths and promoted cyclic deposition.

Locally, the mineralisation of the structures occurs as simple single veins, quartz-wallrock breccias, zones of parallel stringer veins and splay structures. Bifurcations in the major structures enclose mineralised zones up to eight metres in width where tension gash type stringer veins cut across the enclosed rocks. Splay structures enclose similar zones that lessen as the structures diverge. Larger splays will separate up to 20m from their parent structure.

Within structures the highest grades occur in vertical to steeply plunging dilatational shoots that can occupy up to 60% of the structure. Zonation of stibnite is recognized in the metasediments and the monzogranite where it is most strongly deposited within 400m of the surface. Otherwise, individual structures have a consistent mineralogical character with phases occurring in comparatively uniform proportions. Major structures are seen to contain regular mineralisation over strikes of up to 1.2km. These major structures occur within corridors that span up to 10km strike of the Hillgrove Mineral Field.

The Hillgrove Mineral Field is cut by two regional scale faults of east-northeast strike, the Hillgrove Fault on the northern margin and the Chandler Fault on the southern margin. These faults pre-date the mineralisation, with late reactivation opening dilation zones along shear structures between the bounding faults. These dilation zones provide favourable sites for mineralisation. Nearly all the mineralised shears at Hillgrove are associated with a NW trending structural belt between the two faults, with dips commonly 70° to vertical. A major structure running through the centre of the field from Brackins Spur in the south, through the Garibaldi and Eleanora mines, to the Cosmopolitan deposits in the north can be traced over a strike length of 4kms. The Metz Mining Centre is located to the west of this structure.

Gold and antimony mineralisation at Hillgrove are structurally controlled. The deposits exhibit various styles of hydrothermal activity, with veining ranging from simple single veins through parallel stingers to quartz stockwork and wall rock breccias. All major veins have been intruded along shears with left lateral movement. The shears range in width from millimetres to multiple metre widths. Splits in the veins enclose high grade mineralised zones where tension gash type stringer veins cut across the enclosed rocks. Splay veins enclose similar zones that die out as the vein diverges away from the main lode.

All phases occur within ore bearing structures, with the first two phases often sealing structures in the granites resulting from restrictions to later phases. The arsenopyrite phase forms a broad halo of fine parallel veins in a siliceous-sericitic alteration. It appears that all wall rock alteration is associated with this phase, as there is little dispersion of stibnite into surrounding rocks. Alteration effects are commonly on the scale of metres around structures, occurring via pervasive fluid flow, with the more focused quartzstibnite open space filling phase following. The arsenopyrite phase is responsible for most refractory gold in the deposits with the particle free gold associated with the quartz-stibnite-gold phase.

Ore grade material in structures is restricted to vertical or steeply plunging ore shoots, caused by localised flexures forming dilational jogs. The ore shoots generally occupy up to 60% of the structures with good vertical continuity.

Eleanora and Garibaldi Mining Centre
The Eleanora and Garibaldi Lode System is located adjacent to the Hillgrove Processing Plant and 1.5km to the east of the Metz Mining Centre (including Syndicate, Blacklode and Sunlight).

The Eleanora and Garibaldi Lode System is defined over a 1.3km NNW striking shear structure. The mineralisation is generally contained within a narrow shear/breccia that displays multiple hydrothermal fluid events and structural reactivation. The structure and mineralisation are near continuous and contain steeply south plunging shoots of higher-grade Sb-Au mineralisation.

Metz Mining Centre
The Metz Mining Centre is located east of Bakers Creek and 1.5km east of the Hillgrove processing plant. It includes Mineral Resources from the Blacklode, Sunlight and Syndicate lode systems hosted withing the Girrakool metasediments. Blacklode contains east plunging shoots of high antimony and gold mineralisation. Ten lesser subparallel or splaying lodes adjacent to the main shear are included in the Blacklode Mineral Resource.

The Sunlight Lode occurs as a major splay away from the Blacklode structure. Sunlight splays to the south-east as generally two parallel shear/breccia lodes. The structure has been subjected to multiple hydrothermal fluid events and structural reactivation. The intersection of Blacklode and Sunlight Lodes contains high antimony in a limited area. The remainder of the Sunlight Lode is gold dominated with low levels of antimony and tungsten and is more analogous to the Bakers Creek style of mineralisation to the east.

Brackins Spur
The Brackins Spur deposit is located on the southern end of the Central Eleanora Structure, a significant NW trending shear zone that can be traced through several workings for approximately 4km. Hosted in the Bakers Creek diorite, it includes a range of rock types including tonalites, granodiorites and diorites. Strong to intense hydrothermal alteration (predominately sericite) occurs in visibly deformed, veined and mineralised diorite.

Clarks Gully
The Clarks Gully deposit is an advanced antimony project located in the northern most mining lease. The deposit is adjacent to the broad confines of the Hillgrove Fault within the monzogranite, and its large width (up to 10m) is due to the intersection of two structural trends. A pre-existing, ENE trending mylonite zone associated with the Hillgrove Fault is cut by an array of NW striking veins, resulting in a significant dilation zone hosting a mineralised structural breccia. Mineralisation is associated with a network of quartz stringer veins, stockwork and sulphide matrix breccias with intense sericitic alteration of the monzogranite.

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

CommodityProductUnits20222021Avg. AnnualLOM
Gold Metal in conc./ doré koz 41288
Antimony Concentrate kt 5.438
Gold Equivalent Metal in conc./ doré koz 80564

Operational metrics

Metrics20222021
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* According to 2024 study.

Production Costs

CommodityUnitsAverage
Total cash costs Gold Equivalent USD  ....  Subscribe
All-in sustaining costs (AISC) Gold Equivalent USD  ....  Subscribe
All-in sustaining costs (AISC) Gold USD  ....  Subscribe
C1 cash costs Gold Equivalent USD  ....  Subscribe
Assumed price Antimony USD  ....  Subscribe
Assumed price Gold USD  ....  Subscribe
* According to 2024 study / presentation.
** Net of By-Product.

Operating Costs

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

Financials

Units20222021
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Project Costs

MetricsUnitsLOM Total
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OP OpEx $M AUD  ......  Subscribe
UG OpEx $M AUD  ......  Subscribe
Processing OpEx $M AUD 160
G&A costs $M AUD 38
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Required Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Dec 14, 2024
....................... Subscription required ....................... Subscription required Subscription required Jan 7, 2025

Total WorkforceYear
...... Subscription required 2024
...... Subscription required 2022
...... Subscription required 2021

Aerial view:

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