The Bonanza Ledge occurence is located at the divide between Lowhee Creek and Stouts Gulch, 3.5 kilometres south-southeast of the town of Wells.

The Bonanza Ledge occurrence is about 2 kilometres southeast of the main workings of the past-producing Cariboo Gold Quartz Mine (093H 019). It is in the footwall of the northeast dipping B.C.Vein (093H 139), but is about 400 metres southeast of the well mineralized portions of the vein, which saw limited production in the 1940s when it was accessed by an underground extension of the 1500-level crosscut of the Cariboo Gold Quartz Mine. The Bonanza Ledge mineralization occurs in a semi-concordant zone of sericite-carbonate-pyrite-silica alteration within northeast-dipping phyllites of the Upper Proterozoic-Paleozoic Snowshoe Group. The mineralization is distinct from the quartz vein arrays that were exploited at the Cariboo Gold Quartz Mine, but shows similarities to the replacement bodies that were historically mined at the Island Mountain (093H 006) and Mosquito Creek (093H 010) mines a short distance to the northwest (Assessment Report 26604). However, the Bonanza Ledge occurrence is several hundred metres deeper in the structural/stratigraphic succession than the past-producing lode gold deposits in the area (Assessment Report 26604; Fieldwork 2002, pages 77-96), and indicates the potential for mineralization outside areas that had been traditionally thought of as most prospective within the Barkerville gold belt (Geological Survey of Canada Memoir 181).

The Bonanza Ledge gold mineralization occurs in at least three separate zones, referred to as the Discovery zone, the Main zone and the Footwall zone (International Wayside Gold Mines Limited, Press Release, April 19, 2004). The mineralized zones are hosted in a lens of intense sericite-dolomite-silica-pyrite alteration that is up to 100 metres thick. This proximal alteration passes outward into less intense sericite-carbonate (siderite-magnesite)-chlorite-albite alteration, which is fringed by zones of silicification along its outer margin (Assessment Report 26604). The gold-mineralized zones have been traced for about 140 metres along strike (Assessment Report 26604), and the Main zone, from which a bulk sample was extracted, is up to 21 metres thick (International Wayside Gold Mines Limited, Press Release, April 19, 2004).

The mineralized zones at Bonanza Ledge comprise discrete areas of pyrite mineralization that generally contain 10 to 80 per cent pyrite. The pyrite is typically fine grained and occurs in veinlets (with or without quartz-carbonate), concordant laminations, and massive to semi-massive bands up to 60 centimetres thick (Assessment Report 26604). Veinlets and pyrite bands are folded and locally elongated parallel to the fold axes. Intersections from underground drilling on the Main zone, across approximate true widths, include 29.7 grams per tonne gold across 10.5 metres, 26.7 grams per tonne gold across 15.4 metres, and 30.8 grams per tonne gold across 13.6 metres (International Wayside Gold Mines Limited, Press Release, April 19, 2004).

In 2003, International Wayside commenced development of a 140-metre-long decline to access the high-grade Bonanza Ledge gold zone. The exploration program involved 70 metres of trenching in six trenches and 3037 metres of diamond drilling in 26 holes. In 2004, International Wayside Gold Mines Ltd. extracted a 10,000 tonne underground bulk sample on the high-grade gold Bonanza Ledge zone. The head grade of the bulk sample was approximately 23 grams per tonne gold. The company also continued to drill the Bonanza Ledge zone from an underground exploration drift and from surface using a tightly-spaced pattern. In all, 14,142 metres of drilling was completed on the Bonanza Ledge trend.

The 2006 exploration program of International Wayside focused mainly on the Mucho Oro zone which is about 213 metres directly mine-grid-east of the Bonanza Ledge open pit. The Mucho Oro diamond drill program was initiated in order to test a known gold-bearing structure and favorable stratigraphy, east of the Waoming fault and Bonanza Ledge gold deposit. The favorable stratigraphy is that which hosts the pyrite replacement-type gold mineralization in the proposed Bonanza Ledge open pit to the immediate mine-grid-west. A total of 4682.1 metres drilling in 31 surface diamond-drill holes were completed on the Mucho Oro zone in 2006. Of all the 31 drillholes, 26 returned anomalous gold results and 18 of these yielded significant (greater than 1 gram per tonne) gold assays.

Past work in the Mucho Oro area was limited to the mine-grid-west boundary of the area, which includes some diamond drilling, soil sampling, self-potential (SP) geophysics, ground magnetometer and VLF-EM surveys. The SP geophysics outlined a very similar signature to that of the Bonanza Ledge gold deposit, and the ground magnetometer survey indicated the presence of the important marker horizon (magnetic porphyroblastic phyllite of Rainbow 4 Sub-unit) which is in close proximity to the favourable stratigraphy for pyrite replacement-type gold mineralization.

See Cariboo Gold Quartz (093H 019) for related geological details, history and bibliography.

The mineralization does not crop out on surface, but was discovered by International Wayside Gold Mines Limited in March 2000, during a drilling program on the B.C. Vein (093H 139) (International Wayside Gold Mines Limited, Press Release, March 23, 2000). Subsequent drilling included many significant intersections and provided a preliminary outline of the deposit, leading to a 2002 resource estimate by Giroux Consultants Ltd. of Vancouver, which showed indicated resources of 337,478 tonnes grading 8.19 grams per tonne gold, and inferred resources 39,917 tonnes grading 6.14 grams per tonne gold, using a 0.686 gram per tonne gold cutoff (International Wayside Gold Mines Limited, Press Release, December 3, 2002). A bulk sampling permit to mine 10,000 tonnes of Bonanza Ledge ore by way of a 152-metre decline was awarded in October 2003, and underground development commenced a short time later (International Wayside Gold Mines Limited, Press Release, October 14, 2003; November 6, 2003). Mining of an 11,982 tonne bulk sample from three stopes was completed on July 11, 2004. The ore was trucked 256 kilometres to the Mount Polley mill for processing and the concentrate is scheduled to be shipped to Noranda, Quebec, for smelting in early spring 2005 (International Wayside Gold Mines Limited, Press Release, February 23, 2005).

During 2005 through 2008, further programs of diamond drilling were completed. In August 2009, mineral resources for the Bonanza Ledge deposit were reported at 170,846 tonnes measured grading 8.743 grams per tonne gold; 244,156 tonnes indicated grading 6.857 grams per tonne gold and 277,762 tonnes inferred grading 7.783 grams per tonne gold, using a 1.7 gram per tonne (0.050 ounces per ton) cut-off grade (Fier, N.E. (2009-08-17): NI 43-101 Technical Report Pre-feasibility Study of the Bonanza Ledge Deposit). Mineral Reserves were reported at 130,724 tonnes proven grading 10.227 grams per tonne gold and 166,808 tonnes probable grading 8.114 grams per tonne gold, using a 2.8 gram per tonne (0.0828 ounces per ton) cut-off grade (Fier, N.E. (2009-08-17): NI 43-101 Technical Report Pre-feasibility Study of the Bonanza Ledge Deposit).

In 2010, excavator trenching identified a new gold mineralized zone, referred to as the NW and Pit Vein zones, outside (93 metres north west) of the known Bonanza Ledge gold deposit. The new zone comprises a large fault zone with semi-massive or massive fine-grained pyrite replacement and quartz-pyrite veins exposed over a length of approximately 120 metres and a width of up to 26 metres.

In 2011, 231 surface diamond drill holes, totalling 54915.6 metres, were completed on the Barkerville Mountain and Cow Mountain (MINFILE 093H 019) deposits. Trenching on the Pit Vein zone was successful in extending the mineralization into the Myrtle (MINFILE 093H 025) property to the northeast.

On December 5, 2011, Barkerville Gold Mines Ltd. (formerly Wayside Gold Mines Ltd.) announced that they had received a Mines Act permit to develop an open pit gold mine at Bonanza Ledge. In 2012, Barkerville Gold Mines Ltd. announced that they had received an amendment to their Mines Act permit for the mill at the QR mine (093A 121) to process the ore from the Bonanza Ledge open-pit mine.

Production at Bonanza Ledge open-pit mine started in March 2014 and it had a mine life of four years. Ore was processed at the company's QR Mill a hundred kilometres away (Exploration and Mining in British Columbia 2014).

In February 2015, Barkerville Gold Mines put Bonanza Ledge mine on care and maintenance.

The Bonanza Ledge mine saw limited production as an open-pit mine between March 2014 and June 2015. In December 2016, Barkerville Gold Mines Ltd. applied for a permit to mine the remaining resource by underground methods. The company hopes production can resume in 2017. The plan is to mine at a rate of ~500 tonnes per day (~150,000 tonnes per year) using a long-hole method with cemented rock fill.

Barkerville Gold Mines Ltd. restarted the Bonanza Ledge mine in the last week of August 2017 as an underground long-hole and cemented-fill operation below the existing pit. They expect to mine about 30,000 tonnes in 2017 and 150,000 tonnes per year thereafter at 6.5 grams per tonne gold diluted for 3.5 years. Initial life of mine is a planned 3.5 years, but there is exploration potential. Ore is trucked to Barkerville’s QR mill (093A 121).

In 2017, resources were reported as: Measured, 248,000 tonnes at 8.07 grams per tonne gold; Indicated, 436,700 tonnes at 6.72 grams per tonne gold; and Inferred, 108,100 tonnes at 5.34 grams per tonne gold (Information Circular 2018-1, page 88).

In June 2018, an updated mineral resource estimate for the combined Bonanza Ledge, BC Vein, Mosquito, Shaft, Valley and Cow deposits was reported at 8,109,900 tonnes measured and indicated grading 6.1 grams per tonne gold and 12,731,200 tonnes inferred grading 5.2 grams per tonne gold (Beausoleil, C. (2018-06-14): NI 43-101 Technical Report and Mineral Resource Estimate Update for the Cariboo Gold Project).

In 2018, Barkerville Gold Mines Ltd. completed a program geological mapping, channel, rock, soil and underground sampling and 449 diamond drill holes, totalling 128,759 metres, on the Cariboo Gold property.

In late May 2019, an updated mineral resource estimate for the combined Bonanza Ledge, BC Vein, Mosquito, Shaft, Valley and Cow deposits was reported at 13.495 million tonnes measured and indicated grading 5.6 grams per tonne gold with an additional 11.936 million tonnes inferred grading 5.0 grams per tonne gold, using a 3.0 grams per tonne gold cut-off grade (Beausoleil, C. (2019-07-11): NI 43-101 Technical Report and Mineral Resource Estimate Update for the Cariboo Gold Project).

In 2019, Barkerville Gold Mines Ltd. completed a program of geological mapping and 109 diamond drillholes, totalling 45,641 metres, on the Cariboo Gold property. Drilling on the KL zone yielded intercepts of 1.20 grams per tonne gold over 22.55 metres in hole BM-19-009 to 145.00 grams per tonne gold over 0.80 metre in hole BM-19-025 (Beausoleil, C., Pelletier, C. [2020-10-05]: NI 43-101 Technical Report and Mineral Resource Estimate for the Cariboo Gold Project, British Columbia, Canada).

In April 2020, an updated resource was reported for the Cariboo Gold project (Bonanza Ledge [MINFILE 093H 140], BC Vein [MINFILE 093H 139], KL [MINFILE 093H 140], Lowhee [MINFILE 093H 139], Mosquito [MINFILE 093H 010], Shaft [MINFILE 093H 006], Valley [MINFILE 093H 019] and Cow [MINFILE 093H 019] deposits) with a total of 21 441 000 tonnes measured and indicated grading 4.6 grams per tonne gold with an additional 21 649 000 tonnes inferred grading 3.9 grams per tonne gold using a 2.1 grams per tonne gold cut-off grade (Beausoleil, C., Pelletier, C. [2020-10-05]: NI 43-101 Technical Report and Mineral Resource Estimate for the Cariboo Gold Project, British Columbia, Canada).

In 2020, Barkerville Gold Mines Ltd. completed 82 diamond drill holes, totalling 25 397.7 metres, on the Cariboo Gold project.