Nicaragua

Hemco Mine

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Overview

Mine TypeUnderground
StatusActive
Commodities
  • Gold
  • Silver
  • Zinc
Mining Method
  • Shrinkage stoping
  • Sub-level open stoping (SLOS)
  • Longhole stoping
  • Bench & Fill
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SnapshotThe Hemco Property consists of the producing Panama gold mine (Panama Mine, including Panama, Elefante, Toboba, Tesoro, Neblina, Pluto SW, Neptuno, and Capitan veins), the producing Pioneer gold mine (Pioneer Mine, including the Lone Star, Northeast, Pioneer Northeast Extension, and Pioneer 3 veins), the pre-development-stage Porvenir polymetallic deposit, the Luna Roja gold deposit, the Leticia and San Antonio polymetallic deposits, several exploration targets, and a large number of artisanal operations (artisanal areas). The Hemco Property also hosts three processing plants with a combined capacity of 2,000 tonnes per day - the Hemco Plant, the La Curva Plant, and the Vesmisa Plant - which process ore mined from the Hemco Property and locally purchased artisanal feeds, in addition to other project infrastructure.
Related AssetPorvenir Project

Owners

SourceSource
CompanyInterestOwnership
Mineros S.A. 99.995 % Indirect
Hemco Nicaragua S.A. (operator) 100 % Direct
Mineros holds a 99.9975% interest in the Hemco Property through its interest in its subsidiary, Hemco Nicaragua S.A. Mineros holds a 99.995% interest in Hemco Nicaragua directly, and a further 0.0025% interest indirectly through Mineros Aluvial S.A.S. BIC (Mineros Aluvial), a wholly owned subsidiary of Mineros. The remaining 0.0025% interest in Hemco Nicaragua is held by Mercantil Colpatria S.A. (Colpatria), a major shareholder of Mineros. Hemco Nicaragua holds a 100% interest in the majority of the concessions that constitute the Hemco Property.

Contractors

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Deposit type

  • Epithermal
  • Volcanic hosted
  • Vein / narrow vein
  • Skarn

Summary:

The majority of mineralization within the concession area consists of volcanic hosted goldsilver + copper, lead, and zinc epithermal quartz veins of intermediate sulphidation type. There is a vertical zonation of metals and base metal grades are higher at depth, although, in general, gold grades appear to stay constant.

In addition to these epithermal quartz veins, there are several alluvial gold deposits derived from weathering of the mineralized veins and gold mineralization is also hosted within skarns associated primarily with selective replacement of carbonate rocks.

Mineralization at the Hemco Property is hosted in the Panama, Pioneer, and Constancia groups. The Porvenir, Leticia, and San Antonio deposits are within the Constancia Group. Gold mineralization at Luna Roja is hosted within skarns associated primarily with selective replacement of carbonate rocks of the Cretaceous Metapán Formation.

Vein Deposits
The majority of mineralization within the concession area consists of volcanic hosted gold-silver ± copper, lead, and zinc epithermal quartz veins of intermediate sulphidation type. There is a vertical zonation of metals, and base metal contents are higher at depth, although, in general, gold grades appear to stay constant except in those areas near surface where residual gold has been liberated by the oxidation of pyrite and weathering/disintegration of host rock.

The epithermal veins at Bonanza are characterized by moderate to intense propylitic alteration of the andesite wall rocks locally accompanied by argillic alteration and silicification. There are several variations in style of mineralization among the veins.

Veins in the southwest part of the district are characterized by gold mineralization associated with quartz, chalcopyrite, and hematite enriched in base metal sulphides. Gold mineralization in veins toward the northeast, i.e., the Pioneer and Panama groups, is associated with quartz and chlorite and generally lower base metals content. The difference in gold and base metal tenor between the Panama, Pioneer, and Constancia groups may be a function of the spatial relation with the intrusive heat source. Shallow epithermal veins are characterized by low grades but wider zones resulting from bifurcations and quartz stockwork zones. Base metal contents are generally lower at the shallow depths than what has been encountered in deeper parts of the system and trace elements such as strontium and barium are higher. Alteration is characterized by zonation from propylitization of country rocks to argillic alteration as the vein is approached. Silicification can be widespread and intense. Phreatic breccias are common as are boiling textures such as bladed quartz after calcite. Deeper portions of epithermal systems are typically enriched in base metals and have higher gold grades. The veins are more discrete, and alteration is characterized by moderate to strong propylitization of the wall rocks. In the Bonanza district, all of the veins are interpreted to lie in the middle to deeper levels of an epithermal system. On the basis of base metal content, the Porvenir, Leticia and San Antonio veins in the Constancia Group are interpreted to be deeper relative to the Pioneer and Panama groups.

Byington (1996) noted that quartz veins are controlled by strike-slip faulting with both sinistral and dextral displacement and mineralized shoots are controlled by gold deposition introduced during dextral strikeslip movement resulting from wrench tectonics. Gold grades are higher in areas of increased fracture density and permeability such as flexures in strike and dip. This may also account for the observed periodicity of mineralized shoots and non-mineralized portions of the structures. In a very general sense northwest dipping mineralized shoots more often have southwest plunges and southeast dipping shoots have a vertical to steep northeast plunge.

The Bonanza epithermal gold mineralization may be related to a 40 km diameter pluton on the southeast side modeled from pseudo-gravity high. The Siuna and Rosita copper-gold deposits are also on the edges of this interpreted pluton. Recent petrographic studies by Miller (2016) of the Tesoro, Cruzada, and Northeast vein systems concluded that the three epithermal systems record hydrothermal events with similar silicate-sulphide assemblages. A paragenetic sequence was established that can be used as a working model for identifying textures and timing within the complex vein networks. The study documented four textural stages of quartz vein filling termed Q1 to Q4 and corresponding sulphide assemblages termed S1 to S4 which are combined as Q1/S1 to identify the earliest quartz-sulphide event and similarly for younger vein episodes.

Skarn Deposits
The Luna Roja deposit is hosted within skarns associated primarily with selective replacement of carbonate rocks of the Cretaceous Metapán Formation. The Luna Roja skarn shows prograde and retrograde calc-silicate alteration, hosted mostly in carbonate rocks, which led to the formation of redbrown- yellow garnet, green-yellow garnet-pyroxene, and wollastonite.

The skarn in Luna Roja shows different types according to its mineral assemblage and colour: a) a yellowbrown skarn which consists of brown-yellow medium-coarse size grained garnet, with poor presence or absent pyroxene; b) a dark green skarn with pyroxenes with a ratio of 3:1 over garnets, accompanied by amphibole and magnetite; c) a yellow-green skarn, where garnets of this colour are predominant over pyroxenes in a ratio of 6:1 to 9:1; d) a red-brown skarn, which can be found adjacent to igneous subvolcanic bodies, as alteration in veins, layers and patches of red and brown garnet.

Also, a structurally controlled late mineralization system, placed in subvertical structures which are possibly related to northwest regional faulting, is overprinting the skarn deposit. The most important unit of this system consists of a red quartz-calcite hydrothermal breccia, ± hematite ± magnetite ± adularia ± pyrite ± chlorite. The host rock of this system was affected by these oxidized fluids, hence the marble and skarns adjacent show red patches. The nature and timing of this event has not been determined yet.

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

At the Hemco Property in Nicaragua, approximately 70% of the gold produced is purchased from artisanal miners at a percentage of the gold spot price.
CommodityUnits202320222021202020192018201720162015
Gold koz  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe1251071047969
Silver oz  ....  Subscribe  ....  Subscribe  ....  Subscribe
All production numbers are expressed as metal in doré. ^ Guidance / Forecast.

Operational metrics

Metrics20222021202020192018
Daily milling rate  ....  Subscribe  ....  Subscribe  ....  Subscribe1,557 t1,515 t
Daily milling capacity  ....  Subscribe  ....  Subscribe  ....  Subscribe
Tonnes milled  ....  Subscribe  ....  Subscribe  ....  Subscribe

Production Costs

CommodityUnits20232022202120202019
Total cash costs (sold) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 923 / oz **  
All-in sustaining costs (sold) Gold USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 1,103 / oz **  
^ Guidance / Forecast.
** Net of By-Product.

Financials

Units202220212020
Sustaining costs M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
Capital expenditures M USD  ....  Subscribe  ....  Subscribe
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe
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Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Mar 24, 2023
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EmployeesContractorsTotal WorkforceYear
...... Subscription required ...... Subscription required ...... Subscription required 2022
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Aerial view:

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