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File Created: 12-Jan-87 by Mary McLean(MM)
Last Edit:  14-Jun-11 by Sarah Meredith-Jones(SMJ)

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NMI 092J15 Au3
Name BRALORNE, BRALORNE MINE, LORNE (L.588), KING, WOOD CHUCK (L.579), CROWN, WEDGE, QUEEN, MADDIE, PETER, BIG SOLLY, TELEPHONE, TAYLOR, 52, ZONE B, EMPIRE Mining Division Lillooet
BCGS Map 092J076
Status Producer NTS Map 092J15W
Latitude 50º 46' 40" N UTM 10 (NAD 83)
Longitude 122º 49' 20" W Northing 5624910
Easting 512632
Commodities Gold, Silver, Lead, Zinc, Copper, Tungsten Deposit Types I01 : Au-quartz veins
Tectonic Belt Coast Crystalline Terrane Bridge River, Cadwallader
Capsule Geology

The area is underlain by Mississippian-Jurassic Bridge River Complex (Group) and Upper Triassic Cadwallader Group sediments and volcanics which are transected by a major north trending, steeply southwest dipping fault known as the Cadwallader Break. The fault is a deep-seated crustal structure related to the Fraser fault system to the south. The fault is intruded by small granitic to ultramafic stocks and dykes. Diorite to gabbro of the Permian Bralorne Igneous Complex, in which most of the quartz veins are hosted, intrudes the Cadwallader Break as an elongate body. Diorite also intrudes Pioneer Formation (Cadwallader Group) greenstones although at times the contact appears gradational. The diorite and greenstone are in turn "intruded" by sodic granite which may be an apophysis of the Early Tertiary Bendor pluton, the main body of which lies 10 kilometres east. The sodic granite also appears gradational with the diorite and exhibits a migmatitic texture, which has led to the conclusion that it may be a late differentiation of the same magma that formed the diorite. The sodic granite occupies the northwest half of the intrusive belt and narrows out north and south.

A 60-metre wide belt of serpentinite (Bralorne Igneous Complex) borders the diorite on the southeast at the contact with the Noel Formation (Cadwallader Group). Finally, the intrusive belt is intruded by albitite dykes which often follow the chilled margin of the sodic granite, and where associated with quartz veins, the dykes are altered to platy quartz-sericite schist. The principal host rock is the diorite, and an abnormal richness in gold was noted when veins neared the serpentinite; it has been suggested that the serpentinite acted as a dam to mineralized solutions. The veins also followed the albitite dykes and vein structures extend into other rock types (greenstones and sodic granite).

The age of the mineralization is constrained by three sets of isotope data; a zircon from a pre-syn mineralization albitite dike returns 91.4 +/- 1.4 Ma, while a K/Argon from a hornblende and the containing whole rock from a syn-post minerization hornblende porphyry dike is 85.7 +/- 3 Ma. Argon/Argon step heating of associated mariposite gives a minimum age of mineralization of 70 - 80 Ma (Bulletin 108, page 47-48).

The lens hosting quartz veins is five kilometres long by 2 kilometres wide and has a complex interlacing fault system. The main producing veins generally strike east and dip varying degrees to the north, in reverse fault zones extending from the Fergusson fault (northeast dipping) to the Cadwallader fault (southwest dipping). This zone between the faults grows wider with depth, and veins are persistent, having been mined to nearly a 2 kilometre depth. Diagonal "crossover" veins host many secondary veins which are commonly brecciated.

The Bralorne mine is divided into 3 main sections, the Crown, Empire and King. The principal veins in the Crown and Empire sections are known as the 51 and 77 veins, their faulted extensions, the 55 and 53 veins respectively, and crossover veins 59, 73, 75 and 79. The main veins in the King section are the North, Shaft, King, Alhambra and C veins. For descriptive purposes, the 51 (and 55) and 77 (and 53) veins are treated separately, under the names of the original mines, before amalgamation into Bralorne Mines. These are the Ida May mine (Empire and Blackbird) for the 51 vein - see 092JNE002, and the Coronation mine (Little Joe and Countless) for the 77 vein - see 092JNE007. The most prolific vein was the 77.

Generally, the veins average 1.5 metres in width and range up to 6 metres. They are often tabular, well-ribboned or partly ribboned, and partly massive or brecciated. All types have hosted ore, although the best values came from ribboned veins. The gangue minerals are quartz, calcite, mariposite, talc and scheelite. The principal sulphides are pyrite, arsenopyrite and sphalerite, which along with native gold, galena, chalcopyrite, pyrrhotite and tetrahedrite occupy less than one per cent of the veins. Carbonate alteration (siderite) is widespread with albite occurring along vein shears. The Bralorne mine was accessible by 4 main shafts and worked on 44 levels.

Bralorne Pioneer Gold Mines Ltd., in a joint venture with International Avino Mines Ltd., plans to re-open the historic Bralorne mine encompassing the combined Bralorne, Pioneer (092JNE004) and Loco (092JNE164) properties, following issuance of a Mine Development Certificate in March 1995. Initial underground mining will be from the formerly producing Bralorne 51 vein area where detailed exploration programs, in recent years, have outlined proven, probable and possible reserves of 570,000 tonnes grading 8.22 grams per tonne gold. Proven and probable reserves above the 800 level and readily available for extraction total 432,500 tonnes grading 10.63 grams per tonne gold. There are also reserves of 549,125 tonnes grading 9.26 grams per tonne gold below the 800 level (Information Circular 1997-1, page 20). The nearby Countless vein on the Loco property has 110,000 tonnes probable and possible reserves grading 17.1 grams per tonne gold. The Peter vein was drifted along a strike length of 35 metres on the 800 level, 305 metres below the surface (T. Schroeter, personal communication, 1996). Mining and milling operations are forecast to start at about 100 to 125 tonnes per day, increasing to 400 tonnes per day at a later date. Mill tune-up and production is scheduled for mid-March 1997. Milling machinery, purchased from Zeballos, is being assembled at the property and the mill building has been rehabilitated (Information Circular 1996-1, page 17).

In 1995, Bralorne Pioneer Gold Mines Ltd., and partner International Avino Mines Ltd., with support from the Explore B.C. Program, carried out an extensive exploration program including trenching and 650 metres of surface diamond drilling in 7 holes on the Maddie zone resulting in the discovery of new veins. Underground work on the 800 level consisting of 233 metres of drifting, 100 metres of crosscuts and 544 metres of diamond drilling in 4 holes traced the Peter and Big Solly veins to and beyond a crossfault (Explore B.C. Program 95/96 - A32).

In 2003, Bralorne-Pioneer Gold Mines Ltd resumed construction of a 125 tonne-per-day pilot plant test mill and began construction of a tailings pond. Trenching and drilling were done in the area of the Peter, Cosmopolitan and Big Solly veins on the Loco property. Bralorne also did rehabilitation work on the 800 level in the Bralorne mine. In early 2004, Bralorne plans to mine a 6000 to 8000 tonne bulk sample from the Peter vein, which will be processed in the pilot mill. The drilling program consisted of 15 NQ holes totaling 1751.5 metres and was designed to provide additional information on the Peter vein and associated structures in the area beneath the upper level workings and also along strike to the north and south.

In 2004, Bralorne completed construction of a tailings pond to allow five years of production, and began test milling using a small (approximately 100 tonne-per-day) gravity/flotation pilot plant. As of mid-August more than 10 000 tonnes had been processed through the plant, producing about 141 dry tonnes of concentrate. Most of the material processed was from low-grade stockpiles with some additional material coming from the Upper Peter vein (4230 adit) on the Loco (or Cosmopolitan) property. A small amount of dore gold was produced onsite, and about 20 tonnes of flotation concentrate was shipped.

Bralorne also did underground development to prepare a stope on the Peter vein on the 800 level of the King mine workings, and drove a decline from the 4230 level to access a new level 30 metres deeper. Surface drilling returned encouraging results from the 51B vein in the gap between the Bralorne and Pioneer mine workings, and a new 180-metre long adit is being driven to access this area.

The following resource estimates were reported in The Northern Miner, April 4, 2005. It is not known if they are NI-41101 compliant. The measured resource in the Peter vein comprises 3,425 tonnes grading 8.4 grams gold per tonne. The Peter vein has been drifted on top and bottom with samples taken at 1.8 metre intervals across the exposed vein. The upper Peter vein contains another 22,738 tonnes grading 9.7 grams gold in the inferred category. The indicated mineral resource in the 51B FW vein is reported at 17,729 tonnes grading 11 grams gold. The resource was based on 43 diamond drill holes drilled this winter and five historic drill holes. The 51B FW vein intersected by the Area 51 cross-cut yielded considerably higher grades of up to 21.1 grams gold over 1.5 metres. Another inferred resource of 389,964 tonnes grading 10.4 grams gold sits above the 800-level.

In a June 2009 Technical Report on Bralorne Pioneer Mine Property updated resources were 17,627 tonnes measured grading 16.24 grams per tonne Au and 142,330 tonnes inferred grading 14.98 grams per tonne Au calculated at 7.78 grams per tonne Au cut-off(Technical Report June 2009 p.56, http://www.bralorne.com)

Bralorne Gold Mines Ltd. commenced production in May 2011 and is continuing exploration throughout 2011.

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