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Haile UG - Horseshoe Mine

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Summary

Mine TypeUnderground
StatusActive
Commodities
  • Gold
  • Silver
Mining Method
  • Transverse stoping
  • Sub-level open stoping (SLOS)
  • Longhole stoping
  • Transverse stoping
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SnapshotThe Haile underground consists of three deposits: Horseshoe, Ledbetter, and Palomino Underground.

The Horseshoe underground mine began mining in September 2023.

Palomino, Pisces, and Ledbetter Phase 4 are being considered as potential future underground ore sources.

The Palomino Underground operation was approved on March 15, 2024. The permit modification for the method of mining change for Ledbetter Phase 4 to an underground is expected to be completed in 2027 before mining takes place in 2028.

The Palomino Underground begins development in 2026 and reaches first ore in 2028, utilizing existing Horseshoe infrastructure. Ledbetter (LUG) portal construction commences in 2028, with first development ore expected in 2029 and steady-state production expected in 2030.

In 2026, growth capital relates primarily to the Palomino Underground development

Owners

SourceSource
CompanyInterestOwnership
OceanaGold Corp. 100 % Indirect
Haile Gold Mine Inc. (operator) 100 % Direct
The Haile Gold Mine is 100% owned and operated by OceanaGold through its wholly owned subsidiary, Haile Gold Mine Inc.

Contractors

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Deposit type

  • Sediment-hosted

Summary:

Haile is the largest operating gold mine in the eastern U.S. It is situated within the north-east-trending Carolina Terrane, also known as the Carolina Slate Belt, which hosts the past-producing Ridgeway, Brewer, and Barite Hill gold mines in South Carolina. Mineralization at Haile is currently interpreted as a structurally modified, low-sulfidation, disseminated gold deposit. The Haile property consists of eleven gold deposits within a 4 km x 1 km area. The deposits occur within a variably deformed ENE-trending structural zone at or near the contact between metamorphosed Neoproterozoic volcanic and sedimentary rocks. The deposits are hosted in metamorphosed laminated siltstones and volcanic rocks of the Upper Persimmon Fork Formation and are dissected by barren NNW striking diabase dikes. Deformation includes brittle and ductile styles with ENE trending foliation, faults, brecciation, and isoclinal folds. Sedimentary rocks are folded within an ENE trending anticlinorium with a steep SE limb and a gentle NW limb. Foliation dips to NW.

The Haile gold deposits are exposed within a metasediment (MS) window flanked and overlain by MV. Sedimentary rocks are folded within an ENE-trending anticlinorium with a steep SE limb and a moderate NW limb. The MV / MS contact is conformable with bedding. High strain fabrics overprint all metavolcanics (MV) and MS units in the mine area. The ENE-striking MV / MS contact dips 60 to 80 SE along the southeast margin of the district and generally constrains gold mineralization at Red Hill East, Palomino, Deep Snake, and Horseshoe. The MV / MS contact dips 30 to 50 NW in north-central portions of district and caps gold mineralization at Ledbetter, Upper Snake, Mill Zone, and Red Hill West.

The district is dissected by several ENE-striking, 30° to 60° NW-dipping dip- and oblique-slip shears that appear to both focus gold mineralization and displace mineralized zones. The Mill Zone orebody is faulted into two segments with about 100 m of normal displacement. Brittle deformation is characterized by anastomosing fault zones with discrete thin slip planes, commonly filled with ribbon quartz or gouge. Fold axes observed in drilling and mapping mostly occur in the southeast portion of the district in the Red Hill, Palomino, and Snake deposits. Portions of the Ledbetter deposit contain chaotic folds with variable orientations. Fold axes strike N40° E to N70° E and plunge gently east.

Gold mineralization at Haile is hosted by laminated siltstone and felsic volcanics in the Upper Persimmon Fork Formation. Within the laminated siltstone, gold is found at two primary horizons. The primary ore zone is located at upper siltstone / dacite contact where it is capped by less permeable coherent dacite flows. A secondary ore zone is found at the basal siltstone / felsic volcanics contact. The primary mineralization is typically within 100 m of the dacite-siltstone contacts.

Orebody geometry is partly controlled by the variable orientation of volcanic sediment contacts and the location of barren dacite sills. Ore lenses are typically 50 to 300 m long, 20 to 100 m wide, and 5 to 30 m thick. Ore zones are separated by barren siltstone, dacite sills, and diabase dikes. The MV / MS contact and gold mineralization gradually deepen from west to east across the Haile district. The MV / MS contact at Champion has been partly removed by erosion in the west portion of the district while is over 500 m deep at the Horseshoe deposit, 4 km east of Champion. Depth and position of the contact are further complicated by faulting and folding. Drilling in southeast areas around Palomino has encountered gold mineralization up to 1 km deep.

Small, mineralized zones at Ledbetter, Red Hill, Mill Zone, and Snake are hosted in the overlying dacite along fault zones within 15 m of the MV / MS contact. Gold grades in mineralized dacite are typically lower than in the underlying rocks while sericite alteration is more intense in the dacite. Hydrothermal brecciation is common in portions of the Ledbetter, Horseshoe, Small, and Champion deposits where milled, silicified siltstone clasts occur in a fine-grained quartz-pyrite matrix intruded by fingers of quartz feldspar porphyry with quartz stockwork veinlets. The secondary mineralization zone shares many characteristics with the upper zone and includes some classic epithermal features such as banded veining, colloform / crustiform quartz adularia veins with local quartz after bladed calcite, indicative of boiling. Gold grades can be elevated (circa 18 g/t) within these veins but quickly drops off to more typical Haile grades in disseminated mineralization within the surrounding wall rock.

Mineral zonation grades outward from quartz-pyrite ± K-feldspar + gold (QS) / QSP ± gold / sericite + pyrite ± pyrrhotite / chlorite-calcite ± epidote (propylitic). QS and QSP mineralized zones are tens of metres thick. Sericite envelopes range in thickness from tens to hundreds of metres and are controlled by protolith, permeability, and weathering. Within the mineralized zones, quartz is dominant (60% to 80%), pyrite is moderate (1% to 10%), and sericite is variable at 5% to 40%. Semi-massive pyrite zones are locally observed over thicknesses of 0.5 to 5 m, especially in the Mill Zone, Red Hill and Haile pits.

Early pervasive, replacement-style sulfidation and silicification is overprinted locally by hydrothermal brecciation, quartz stockwork veining, and cm-scale quartz-pyrite veining. These secondary features generally define the high-grade zones within an ore body. Pyritized and sericitized envelopes extend beyond the silicified ore zones, are elongated parallel to foliation, and broadly define the 0.1 g/t Au shell. Pyrite grain size is typically less than 20 microns (µm) in ore zones. A late phase of barren, coarse, cubic, undeformed pyrite that formed during regional greenschist metamorphism is present outside of mineralized zones. Pyrite cubes in chloritic metamorphosed rocks are 0.5 to 1 mm in size but can be as large as 1 to 2 cm. Pyrrhotite commonly occurs in 5 to 25 m thick halos around and on the edges of ore zones but is sometimes present within the deeper, underground deposits. Its ductile nature produces length; width ratios more than 5:1 in foliated rocks. Pyrrhotite formation is interpreted to be coeval with early, fine-grained pyrite precipitation.

Gold spatially correlates with silver, arsenic, molybdenum, and tellurium. Base metals are rare at Haile. Thin section petrography and scanning electron microscopy show that the gold occurs as native gold, gold-pyrite, gold-pyrite-pyrrhotite clusters in fine-grained silicified zones, and in Au tellurides. Gold tellurides are more common deeper in the system at the Clydesdale and Ledbetter Underground zones. Smeared molybdenite occurs primarily on foliation surfaces and as fine-grained aggregates in silicified zones. Molybdenite at Haile has been dated by Re-Os isotopes at 553.8 ± 9 Ma (Stein et al., 1997), which is coeval with the zircon crystallization age of 553 ± 2 Ma reported by Ayuso et al. (2005). This age correlation indicates that molybdenite mineralization was concurrent with Persimmon Fork volcanism. Seven Re-Os molybdenite ages from Haile (Mobley et al., 2014) yielded ages ranging from 529 to 564 Ma. Four of these samples produced an average age date of 548.7 ± 2 Ma (Mobley et al., 2014).

Reserves

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Mining Methods

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Required Heavy Mobile Equipment

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Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

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Commodity Production

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Operational metrics

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Production Costs

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Operating Costs

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Personnel

Mine Management

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