Black Hills, South Dakota initial mining 1874. Rich Banded Iron Formation Gold Belt – Hosting more than 62 million ounces of gold.
- Stable Government
- Good Infrastructure
- Wharf Strip Mine still producing gold
- Agnico exploring; Gilt Edge-Homestake area 20 core holes for gold
- Experienced workforce
- Supportive legislation
- Ubiquitous Placer gold
MMV has evolved from exploration in the Rochford area to resource definition. There is a closely spaced cluster of 5 gold prospects of which 2 have been elevated to the resource/reserve evaluation stage. MMV envisions the potential for 3-5mm Au ounce per prospect.
The grouping would allow for a centralized processing facility. The MMV proprietary EM/aeromagnetics data has tied the group of five to other exploration prospects within the Rochford Gold District.
Looking West at the Homestake Mine Model
- 125 years of operation, discovered in 1876, and closed in 2001 due to low gold price; it did not run out of gold mineralization
- >42M oz Au production from 152 Mt @ 8.4 g/t Au
- Open below 8500-foot level
- Largest iron formation hosted gold deposit in the world
7430-ft. Level: Quartz vein in Homestake Formation with arsenopyrite and pyrrhotite
Homestake BIF Gold Ore Ledges
- 11 gold ore ledges were mined at Homestake, averaging 8.38 g/t Au.
- The Main Ledge was 74m tonnes (19.07m oz. Au produced)
- 9 Ledge was 36m tonnes (9.50m oz. Au produced)
Ledge
g/t Au
Mt
Au (M oz)
Caledonia Ledge
7.43
4.90
1.06
Main Ledge
8.73
74.00
19.07
7 Ledge
7.31
4.80
2.00
9 Ledge
9.05
36.00
9.5
11 Ledge
7.87
7.10
1.62
13 Ledge
8.71
2.20
0.56
15 Ledge (est.)
9.10
3.75
1.00
17 Ledge
6.94
7.00
1.42
19 Ledge
7.03
2.30
0.47
21 Ledge
8.34
9.40
3.50
23 Ledge
-
-
0.52
Summary
Weighted average g/t Au - 8.38 g/t
Total Metric Tonnes (Millions) 151.45 M Oz Total Au
As of 1992: 36.28 M oz. produced; 4.45 M oz. Reserves (23 Mt @ 6 g/t)
“The district-scale potential for BIF-hosted gold deposits is the attribute that places this deposit type on the radar of both juniors explorers and major producers. Like VMS deposits, they are often found in clusters. This characteristic is highly attractive to major gold companies looking for new deposits that can be developed into mines with longevity.”
Banded iron formation-hosted gold deposits are attractive targets thanks to their potential for large, district-scale gold mining. Although large, low-sulfidation epithermal gold and sediment-hosted Carlin-type deposits get the most attention from today’s gold mining news, banded iron formation-hosted gold deposits rank highly amongst the world’s most attractive exploration targets. While not as common as other greenstone-hosted orogenic gold deposits, gold-bearing BIFs occur in Archean to Proterozoic-age cratonic greenstone belts all around the world. The best examples of BIF-hosted gold deposits are found in Canada, the United States, Western Australia, Brazil, Zimbabwe and India.
Located in the eastern margin of the Wyoming Archean craton in South Dakota, the Homestake mine was North America’s largest and deepest gold mine prior to its closure in 2002. During its 125 year mine life, Homestake reportedly produced >42 million ounces of gold and was the second largest gold producer in the United States after the Carlin district in Nevada. One of Canada’s largest producing gold mines is a BIF-hosted gold deposit located in the province of Ontario. Newmont Goldcorp’s 4,000 tonne per day operation at the Musselwhite mine went into commercial production in 1997 and since then has produced more than 4 million ounces of gold with gold recoveries of 96 percent. Today, Musselwhite has proven and probable gold reserves of 1.85 million gold ounces, measured and indicated resources of 310,000 gold ounces as well as inferred resources of 1.17 million gold ounces.
Homestake / Standby Comparison
- Standby Phase 1 drilling: Gold increases down plunge from:
- 2.0 g/t Au over 3.2m in ST18-001, to
- 1.1 g/t Au over 6.4m in ST18-002, to
- 2.8 g/t Au over 6.1m in ST18-003,
and down-dip to - 2.12 g/t Au over 20m
(including 4.39 g/t Au over 2.5m and 5.24 g/t Au over 1.5m) in ST18-006.
- By comparison, within the surface expression of Homestake 9 Ledge upper tail, rock samples assay only 0.10 g/t Au to 1 g/t Au, with one higher-grade sample assaying 4.5 g/t Au.
- However, alteration characterized by quartz veins with well-developed hydrothermal chlorite selvages and minor sulfides, is locally well developed in the upper tail.
- Consistent ore grade mineralization (~8 g/t Au over 5-10m widths) in 9 Ledge does not begin until 1200m down plunge (800m vertical depth), and the highest Au grades and widths in the 9 Ledge Centroid do not occur until 2000m down plunge (1000m vertical depth).
The Standby gold mine is located about 0.5 miles east of the town of Rochford, South Dakota There are 7 patented lode claims and one mill site claim on the property for a total of about 72 acres of ground. Favorable geology and gold mineralization continues to the south and southeast onto unpatented ground controlled by Mineral Mountain Resources. The Standby mine in 1879 had a 40-stamp mill and used a flume to haul water and create power. This mine and the mill contributed to much of Rochford’s growth in the late 1800’s which at one time was estimated to be about 1,000 people.
Allsman (1940) estimated that roughly 50,000 to 60,000 tons of ore was mined, mostly from near surface oxidized ores. Historic reports indicate that after the oxidized ores had been exhausted in the early 1900’s, the mine operators found it difficult to recover more than 30% gold from the unoxidized ores and the mine shut down.
The Standby Mine deposit, was mined historically at an average grade of about 0.350 ounces per ton (12.0 grams per tonne) in the early 1900’s to the 425-foot level.
Homestake Mining Co.’s – Standby area core hole SM87-3A assayed 10.29 g/t Au over 3.05 m, 4.61 g/t Au across 12.19m and 2.02 g/t across 14.0 meters.
MMV 2018-2020 extended the mineralization to a plunge length of 850 metres (2,788 feet).
MMV 2018 results gold mineralization from 2.0 g/t Au over 3.2 m in ST18-001, to 1.1 g/t Au over 6.4 m in ST18-002, to 2.8 g/t Au over 6.1m in ST18-003.
MMV 2019 ST19-11 multi-core hole intersected multiple intervals of extensive hydrothermally altered iron formation with every interval carrying gold mineralization. This intersected a 6.09-metre interval of up to 80% arsenopyrite mineralization with quartz between 373.80 -379.89 metres grading 1.81 grams per tonne Au, including between 373.80 -374.40 metres grading 7.59 grams per tonne Au and between 378.64 -379.89 metres grading 4.21 grams per tonne Au.
Drilling the Standby prospect has defined the identical geologic characteristics encountered in the Homestake Mine, including iron formation hosted gold mineralization. The iron formation is characterized by quartz veining, hydrothermal chlorite alteration and arsenopyrite. The alteration zones are focussed along wide vertical shears. The Standby prospect historical and MMV drilling consists of 16,360m (53,677‘) in 45 core holes. MMV has defined a 200m (656’) wide gold bearing shear zone to a total vertical depth of 1,000 m (3281’).
The Standby Mine deposit, was mined historically at an average grade of about 0.350 ounces per ton (12.0 grams per tonne) in the early 1900’s to the 425-foot level. This is remarkable as the amalgamation of coarse ground arsenopyrite ore generally had only 30% recovery in the early 1900’s.
Standby Mill
Drilling Results
Intense quartz – sulphide – chlorite alteration over wide intervals, example from near Target 1 area
Standby DDH ST18-006 Upper Tail Core Sample (below) Compared to Homestake 9 Ledge Sample (above) Similar Arsenopyrite & Chlorite Content
Rochford Gold District Potential
- Standby Mine Trend (as discussed); Cochrane Mine Trend Non NI 43-101 compliant inferred resource of 268,000 oz @ 6.34 gpt Au, where MMV holds the down plunge extension; ~10 other early 1900s small mines in District
- Majority of historic drill holes in District are shallow; most were focused on Cochrane resource; little or no drilling in remainder of District; No drilling since 1997
At least 6 high priority ledge-style gold target trends have been defined to date by MMV - Each target trend has space to host a multi-million-ounce gold resource, comparable to a Homestake Mine Ore Ledge
- Currently permitting drill sites for Cochrane Trend and other Target Trends in the District
The Cochrane Gold Mine and Mineral Mountain’s adjoining claims occur within a 3 km long major structural corridor of a fold-thickened iron formation that hosts near surface gold mineralization. The most advanced gold zone, at the up plunge surface expression of this trend is the Cochrane Mine deposit which is estimated to host, based on drilling by Noranda, Getty, Newmont and Naneco Resources, an in-house non-compliant NI43-101 resource estimate of 68,000 ounces of gold in the indicated category and 200,000 ounces of gold in the inferred category grading a combined 6.3 g/t Au to a depth of 165 meters.
Naneco, intersected the down plunge extension of the Cochrane Mine deposit between the lower limits of the non-compliant resource and 100 meters from the South boundary. NM96-5 intersected 9.86 g/t Au over 2.74m and three separate high grade mineralized intervals were cut NM96-7 grading 10.04 g/t Au over 5.03m, 10.25 g/t Au over 2.44m, and 10.87 g/t Au over 2.74m. The latter drill hole, NM-96-7, is only 100 m up plunge from the Cochrane Mine deposit/MMV property common boundary.
The Cochrane prospect historical drilling consists of 12,536m (41,130‘) in 62 core holes. A non-compliant NI43-101 had indicated & inferred resource of 268,000 ounces of gold grading 6.3 g/t (.185o/t) Au to 165m (541’) vertical depth.
