Kidd Mine
The Kidd Mine, also known as Kidd Creek Mine, is an underground base metals operation located approximately 24 km north of Timmins, Ontario, Canada, extracting primarily copper, zinc, and silver from a volcanic-hosted massive sulfide deposit formed around 2.7 billion years ago.[1][2][3] Operated by Glencore Canada since its acquisition, the mine began production in 1966 following discovery in late 1963, initially as an open pit before transitioning to underground mining in 1972, and it holds the distinction of being the world's deepest base metal mine below sea level, with active depths reaching over 9,800 feet (3,000 meters).[4][5][6] Annually producing around 40,000 tonnes of copper and 70,000 tonnes of zinc, the operation has extracted over 171 million tonnes of ore to date, yielding more than 3.8 million tonnes of copper and 9.7 million tonnes of zinc, while supporting significant employment in the Timmins region as one of its largest private-sector employers.[6][7] In December 2024, Glencore announced the mine's closure at the end of 2026 due to reserve depletion, marking the end of over five decades of continuous production.[8]History
Discovery and Early Exploration
The systematic exploration program that culminated in the discovery of the Kidd Creek massive sulfide deposit originated in the early 1950s, driven by Texas Gulf Sulphur Company's adoption of emerging concepts in syngenetic volcanogenic massive sulfide formation within Archean greenstone belts of the Canadian Shield.[9] This approach integrated geophysical surveys, including airborne electromagnetics and magnetics, with geological mapping to target potential submarine exhalative deposits analogous to those observed in modern seafloor settings.[9] By the early 1960s, Texas Gulf had narrowed focus to the Timmins area in northeastern Ontario, where prior regional surveys indicated favorable volcanic stratigraphy and alteration signatures associated with base metal sulfides.[10] On November 7, 1963, Texas Gulf exploration geologist Ken Darke directed a diamond drilling crew to commence hole K-55 on a prospective site approximately 100 kilometers north of Timmins, guided by local geophysical anomalies and stratigraphic correlations.[11] Drilling intersected significant massive sulfide mineralization starting at a depth of about 120 meters, with assays confirming high-grade copper, zinc, and silver content in pyrite-chalcopyrite-sphalerite assemblages within rhyolitic volcanics.[4] Subsequent core analysis revealed an orebody estimated at over 100 million tons, marking one of the largest volcanogenic massive sulfide discoveries in North America at the time.[9] Early post-discovery exploration from late 1963 into 1964 involved rapid delineation through additional drill holes to define the orebody's extent, confirming a tabular lens approximately 1,800 meters long, 300 meters wide, and up to 30 meters thick at shallow depths.[10] Surface geophysical follow-up and underground drifting validated the deposit's continuity, while metallurgical testing established viable recovery processes for the polymetallic sulfides.[9] These efforts, conducted under secrecy to manage speculation risks, underscored the causal link between targeted geophysical targeting and empirical drill validation in high-risk greenfield exploration.[12]Initial Operations and Expansion
Mining at the Kidd Creek deposit commenced in spring 1966 with open-pit operations, managed by Texasgulf Metals Company, following the deposit's discovery in 1963.[13] [14] The first ore shipment to the on-site mill occurred on November 7, 1966, marking the start of concentrate production for copper, zinc, and silver.[13] [15] As the open-pit resources were depleted, operations transitioned to underground mining in 1972, with the development of initial shafts to access deeper massive sulphide ore bodies.[5] [2] This shift enabled sustained extraction using blasthole stoping methods, supported by cemented backfill for ground control.[2] Early underground development focused on No. 1 Mine, extending vertically to exploit the steeply dipping ore zones north of Timmins, Ontario.[15] Expansion accelerated in the mid-1970s with the initiation of No. 2 Mine to accommodate increasing ore throughput, achieving full production capacity of 273,000 tonnes per month by 1977.[16] These developments included shaft sinking and level expansions, replacing the original open-pit infrastructure and boosting annual output toward several million tonnes of ore.[15] [5] By the early 1980s, the operation comprised multiple interconnected underground workings under Texasgulf's management, prior to ownership changes.[15]Ownership Transitions
The Kidd Creek Mine, initially developed by Texas Gulf Inc., an American company, following its discovery in 1963, remained under Texasgulf ownership until 1981.[4][17] In July 1981, Texasgulf transferred control of the mine to the Canada Development Corporation (CDC), a Canadian government-owned entity, as part of a share exchange deal where CDC traded its 37% stake in Texasgulf for the asset.[18][15] This transition marked a shift to Canadian public sector control, with the CDC operating Kidd Creek Mines Ltd. as an integrated mining and milling complex focused on copper, zinc, and silver production.[15] On December 31, 1985, Falconbridge Ltd., a Canadian mining firm, acquired Kidd Creek Mines Ltd. from the CDC for $615 million, integrating it into its portfolio of base metals operations.[19] The deal allowed the CDC to retain a 20% equity interest in Falconbridge, reflecting a privatization move that ended direct government ownership while maintaining Canadian roots for the asset.[19] Under Falconbridge, the mine underwent expansions, including deeper shaft developments, to sustain long-term production amid fluctuating metal prices.[10] Falconbridge's ownership persisted until August 2006, when Xstrata plc, a Swiss-based multinational, completed its takeover of Falconbridge for approximately $6 billion in cash and shares, thereby assuming full control of Kidd Creek.[2] This acquisition expanded Xstrata's North American copper and zinc assets, with Kidd Creek becoming a key underground operation in its portfolio.[2] In February 2013, Glencore International plc merged with Xstrata in a $30 billion all-share deal, forming one of the world's largest mining and commodities trading companies and placing Kidd Creek under Glencore's ownership, where it has operated until the announced production cessation at the end of 2026.[20][21] These transitions reflect broader industry consolidation trends, driven by economies of scale and global metal demand, though they also introduced operational challenges such as periodic suspensions during low-price cycles.[10]Recent Operations and Closure Announcement
Glencore's Kidd Operations maintained active underground mining and processing at the Kidd Mine through 2024 and into 2025, focusing on copper and zinc extraction while implementing safety innovations and closure preparations amid declining ore reserves.[22] The facility, recognized as the world's deepest base-metal mine operating below sea level at depths exceeding 9,800 feet, continued to prioritize worker safety and operational efficiency in its final production phase.[1] Mine management emphasized ongoing business opportunities, including potential partnerships or alternative uses for infrastructure, while advancing environmental rehabilitation plans aligned with industry standards.[23] On December 2, 2024, Glencore informed employees of the decision to cease mining production at the Kidd Mine by the end of December 2026, marking the formal closure announcement after over six decades of operations.[24] A company spokesperson confirmed the timeline on December 3, 2024, attributing the shutdown to the exhaustion of economically viable reserves, with post-closure activities to include site decommissioning and restoration beginning in 2027.[8] This decision, announced in the fourth quarter of 2024, allows for approximately two additional years of production to maximize remaining resources before transitioning to full closure protocols.[7] Glencore has expressed openness to external discussions regarding future site utilization, though no specific alternatives have been finalized.[25]Geology
Formation and Geological Context
The Kidd Creek deposit, located in the Timmins-Porcupine mining district of the Archean Superior Craton, formed within the Abitibi greenstone belt as a volcanogenic massive sulfide (VMS) system during the late Archean.[5] The host Kidd Volcanic Complex consists of a stratified sequence exceeding 2 km in thickness, beginning with up to 500 m of carbonate-altered komatiitic flows and sills overlain by tholeiitic basalt, dacite, and rhyolite, with the ore lenses primarily hosted in felsic volcanic and volcaniclastic units such as massive rhyolite flows and domes.[5] This bimodal-mafic to felsic volcanic succession reflects extensional tectonics in a submarine arc or back-arc rift setting, analogous to modern intraoceanic basins like the Lau Basin, where hydrothermal convection was driven by magmatic heat.[26] Mineralization occurred through the circulation of heated seawater interacting with underlying volcanic rocks, leaching metals (primarily copper, zinc, and associated silver, lead, and gold) and discharging them via focused vents to precipitate as stratabound sulfide lenses on or near the seafloor around 2.7 billion years ago.[3] U-Pb zircon geochronology constrains the volcanic footwall to approximately 2712–2710 Ma, with monazite in alteration halos dating to 2659 ± 3 Ma, indicating rapid sulfide deposition rates of 10–100 tonnes per year during peak hydrothermal activity.[27][28] Stringer veins and massive sulfides (dominated by chalcopyrite, sphalerite, and pyrite) exhibit footwall stringer zones up to 100 m thick and hanging-wall alteration pipes extending 300 m vertically, evidencing fluid focusing along synvolcanic faults and rhyolite feeder structures.[13] The deposit's preservation stems from rapid burial under subsequent volcanic units and minimal post-depositional deformation, though regional metamorphism to greenschist facies and faulting have influenced its structural geometry, with the main orebody dipping 75–80° northwest and plunging moderately.[5] This geological framework underscores the causal role of episodic felsic volcanism in generating large VMS systems, where high heat flux and permeability contrasts enabled sustained metal transport and exhalation.[29]Ore Body Characteristics
The Kidd ore body comprises three geochemically distinct sulfide lenses—North, Central, and South—arranged as parallel, overlapping, elongate flattened cylindrical masses within the Archean Kidd Volcanic Complex.[5][30] These orebodies exhibit a steeply dipping tabular to stratiform geometry, striking north-south and plunging more than 3,000 meters vertically from near-surface to depths exceeding 3 km, with individual lenses typically 100 to 400 meters wide and around 30 meters thick.[5][31] Hosted primarily in felsic rhyolitic volcaniclastic rocks and high-silica rhyolites dated to 2.717 to 2.711 Ga, the mineralization formed as volcanogenic massive sulfide (VMS) deposits along a graben boundary fault, with footwall komatiites and overlying tholeiitic basalts.[5][30] The ore occurs as massive, banded, brecciated, and bedded sulfides, including stringer zones, with replacement of footwall volcaniclastic units and associated hydrothermal alteration halos of sericite, chlorite, quartz, and Fe-rich carbonates.[31][5] Primary sulfide minerals include pyrite (dominant, forming pyritic tops and fringes), sphalerite (Zn-rich interiors), chalcopyrite (Cu-rich bases), pyrrhotite, and galena, accompanied by accessory phases such as tetrahedrite, arsenopyrite, bornite (in the South orebody), cassiterite, and silver-bearing minerals.[30][5] Zonation reflects depositional temperature gradients, with low-temperature Zn-Pb-Ag-Sn-As-Sb assemblages in upper lenses (~250°C) and high-temperature Cu-Co-Bi-Se-In pulses in lower zones under low fO₂–fS₂ conditions, evidenced by sulfur isotope ratios near 0‰.[30] Over 60 ore and gangue minerals have been identified, including trace Co-As, Cu-Sn, and selenides.[30]Mineral Resources and Reserves
The Kidd Mine, operated by Glencore, reports its mineral resources and ore reserves in compliance with National Instrument 43-101 standards for Canadian projects, with classifications based on geological confidence, economic viability, and modifying factors such as mining method, metallurgical recovery, and commodity prices.[32] As of December 31, 2024, measured and indicated mineral resources totaled 3.5 million tonnes at average grades of 3.44% zinc, 1.40% copper, and 41 grams per tonne silver, reflecting updates from drilling, mine design revisions, and depletion due to ongoing underground extraction.[32] Inferred resources were not reported for this period, indicating limited lower-confidence tonnage beyond indicated categories.[32] Proven and probable ore reserves, convertible from resources after applying economic cut-offs and operational factors, stood at 2.8 million tonnes grading 3.46% zinc, 1.32% copper, and 42 g/t silver as of the same date, sufficient to support operations until the announced closure at the end of 2026.[32] These reserves decreased from 2.5 million tonnes in 2023 (at 3.12% zinc, 1.44% copper, 38 g/t silver) primarily due to mining drawdown and design optimizations, with no significant additions from exploration offsetting depletion.[32][33] Lead content remains negligible, consistent with the volcanogenic massive sulfide deposit's primary mineralization in zinc, copper, and silver.[32]| Category | Tonnage (Mt) | Zn (%) | Cu (%) | Ag (g/t) |
|---|---|---|---|---|
| Measured Resources | 3.1 | 3.42 | 1.38 | 42 |
| Indicated Resources | 0.3 | 3.42 | 1.38 | 42 |
| Measured + Indicated | 3.5 | 3.44 | 1.40 | 41 |
| Proved Reserves | 1.5 | 3.42 | 1.41 | 40 |
| Probable Reserves | 1.3 | 3.51 | 1.23 | 45 |
| Total Reserves | 2.8 | 3.46 | 1.32 | 42 |