Richmond Hill Gold Project is owned directly 100% by Homestake Mining Company of California (HMCC), a fully owned subsidiary of Barrick Gold Corporation.
It is operated by DTRC LLC (a wholly owned subsidiary of Dakota Gold Corp.) under an exclusive option to purchase the property (through December 31, 2028):
• Signed (Oct 14, 2021) - 400,000 Dakota Gold shares + three $100k/yr payments - buys exclusive right to purchase; title stays with HMCC during the option;
• To exercise (transfer title): Assume bonds/liabilities + issue +400,000 shares + grant 1% NSR (gold) - title moves to DTRC;
• Amendment (Sep 8, 2022): Deadline - Mar 7, 2026; +>560 acres added; +180,000 shares to Barrick;
• Amendment (Feb 3, 2025): Deadline - Dec 31, 2028; add three $170k/yr payments starting Mar 1, 2026;
• Shares: Total at signing + exercise = 980,000; issued to date = 580,000 (400k + 180k);
• If exercised vs lapses: Exercise - DTRC owns, Barrick keeps 1% NSR; Lapse - HMCC (Barrick) keeps title.
- subscription is required.
Summary:
Deposit Type
Mineralization at the Richmond Hill Gold Project is dominantly replacement style within Tertiary aged breccias of host Precambrian metasedimentary and Cambrian-Ordovician sedimentary rocks. Gold bearing fluids possibly derived from Tertiary intrusions migrated along steeply dipping fractures called verticals, and gold was deposited in favorable structural or chemical traps as replacement deposits. Breccia pipes within Precambrian metasediments and the Cambro-Ordovician Deadwood Formation are the most common gold-bearing host rocks.
Mineralization
The genetic model is that Tertiary-aged gold and silver-bearing fluids possibly derived from the Tertiary intrusions migrated along steeply dipping fractures called verticals, and gold was deposited in favorable structural or chemical traps as replacement deposits. Breccia pipes within Precambrian metasediments and the Cambro-Ordovician Deadwood Formation are the most common gold-bearing host rocks. These breccia pipes are associated with Tertiary alkalic magmatism that generated most of the Tertiary-aged gold deposits in the Homestake District.
Dakota Gold's exploration program seeks to confirm and expand upon known oxide gold resources and test the extent of gold sulfide resources. The zones included within the mineral resource estimate are Richmond Hill, Richmond Hill North, Cleveland, Turnaround, Twin Tunnels, Cole Creek, and MW3.
Local Geology
The Property is on the northwestern portion of the Lead dome, a subsidiary dome north of the main Black Hills uplift. The Lead dome developed in response to a major Tertiary intrusive event that also led to the development of the Tertiary-aged gold deposits. These Tertiary intrusive rocks have a wide range of compositions and occur as stocks, sills, dikes, laccoliths, and breccia pipes.
Richmond Hill
The Richmond Hill Gold mine is centered on an elongate Tertiary breccia pipe intruded into Precambrian phyllite and amphibolite, with stockwork zones fracturing and mineralization surrounding the pipe. The mine is the only site within the Project that has had recent mining. Mining activities were limited primarily to the oxidized cap, although some sulfide-bearing material was also mined. The geology of the Richmond Hill gold mine is as follows:
The (Richmond Hill) breccia pipe contains angular clasts of Tertiary intrusive rock and Precambrian metavolcanic rocks in a matrix of rock flour, iron oxides, barite, and adularia. Accessory minerals in the breccia include quartz, alunite, jarosite, kaolinite, fluorite, and rutile. The breccia is argillically altered and weakly silicified. Pyrite and marcasite occur in unoxidized rock. The deposit (that was mined) was primarily in the oxidized zone which extended to a depth of 250 ft. Gold grain sizes were determined by scanning electron microscope studies to be less than 2 microns (µm) occurring in quartz, feldspar, kaolinite, and iron oxides. (Paterson et al., 1988)
The breccia pipe and enclosing rocks are oxidized up to 250 ft deep, resulting in a hematitic-jarositic cap. The hydrothermal breccia pipe hosts gold, two zones of altered and stockwork-fractured Precambrian schist lying on the eastern and northwestern edges of the pipe, and one zone of stockwork-fractured trachyte porphyry intrusion southwest of the pipe. Gold is widespread, occurring as small native particles near oxidized-pyrite sites.
The sulfide resource underlying the Richmond Hill deposit’s westernmost zone of oxidized and fractured Precambrian rocks is a zone of mineralized sulfide-bearing rock not suitable for heap leaching. The host rock contains pyrite and arsenical marcasite averaging 5% to 10%, locally reaching 25% (Duex’s, 1988 edit of Paterson, 1988). The best grades intercepted to 1986 were 0.22 oz/ton Au over 135 ft, which is approximately 150 ft below the oxide–sulfide interface (St. Joe, 1986).
Richmond Hill North
The Richmond Hill North zone Is approximately 3,000 ft north-east of the Richmond Hill gold mine. The area has three intrusive bodies and a large breccia pipe where early drilling returned mixed results. The geology comprises Proterozoic metavolcanic and sedimentary rocks overlain by the Cambro-Ordovician Deadwood Formation and intruded by Tertiary porphyritic intrusive rocks (LAC, 1993).
Twin Tunnels
The Twin Tunnels zone is 2,900 ft northeast of the Richmond Hill gold deposit at the headwaters of Cole Creek. The Southern Extension is a mineralized Tertiary breccia whereas the Northern Extension is a Tertiary intrusive complex (Watson, 1990).
Gold mineralization at the Twin Tunnels Southern Extension is within silicified Precambrian rocks surrounding a jasperoidal core (St. Joe, 1986). Gold grades in jasperoidal rocks range from 0.15 to 0.25 oz/ton Au. Only the southern portion of the breccia is mineralized, although the breccia continues to the north beyond drill-tested ground.
Turnaround
The Turnaround prospect is 1,000 ft northeast of the Richmond Hill gold deposit and is a breccia pipe overlain by an unmineralized porphyry cap. Bedrock oxidation extends to over 400 ft below the overburden–bedrock interface, and sulfide pods are found randomly throughout the host stratigraphy, suggesting that primary sulfide mineralization was oxidized during the late stages of hydrothermal alteration and more recent weathering (Paterson, 1988). The pipe is weakly mineralized throughout, with a higher-grade section along the southeast margin.
Cleveland
The Cleveland area is about 2,000 ft northeast of the Richmond Hill gold deposit. It contains high-grade Homestake-type mineralization in Precambrian iron formation amphibole schist and metasediments affected by three periods of later folding. Most gold mineralization is controlled by east–west fault systems (Duex, 1989).
MW-3 area
The MW-3 area is approximately 6,000 ft northeast of the Richmond Hill mine and comprises two zones—Main and East—which were reported to have bulk-mineable oxide resources, but were never mined (LAC, 1991). The zone contains the Richmond Hill mine’s processing facility on the northern portion.
The southern part of the MW-3 area is underlain by Precambrian metasediments containing iron formations, whereas the northern portion is overlain by the Cambro-Ordovician Deadwood and Winnipeg Formations, which dip northerly at 15 to 20 degrees. Intruding the sediments are Tertiary monzonitic porphyry dikes and sills, as well as stocks and associated breccia bodies.
Gold mineralization at MW-3 occurs throughout the Deadwood Formation, and less so within unconformably underlying Precambrian metasediments. Potential bulk-mineable material is disseminated in the basal conglomerate and sandstone members of the Deadwood Formation, and uppermost Precambrian schists (LAC, 1991). Steeply dipping and north-northwest-striking fractures known locally as verticals also control replacement gold-mineralization to a lesser extent. The basal contact between Cambrian and Precambrian rocks is strongly oxidized glauconitic limestone, shale, and occasionally massive limestone beds. Underlying Precambrian metasediments comprise mica schist, iron formation, and clastic quartzites with interbedded mica schists. The best gold grades are found within iron formation rocks, and most continuously in oxidized schists. Gold occurs erratically within structures up to 50 ft below the zone of oxidation.