Giant Copper deposit, New Westminster Mining Division, British Columbia, Canadai

Regional Level Types
Giant Copper deposit	Deposit
New Westminster Mining Division	Division
British Columbia	Province
Canada	Country

Porphyry copper deposit.
The Giant Copper developed prospect is located 1.5 kilometres east of the Skagit Valley Recreation area boundary and 2 kilometres due south of Silverdaisy Mountain. The mine area is within an enclave between the E. C. Manning and Skagit Valley Provincial Parks.
There is an extensive description of the property on the B.C. Government site “Minfile”- Minfile No. 092HSW 001, current to 2017, to which interested readers are referred. The following quote describes the mineralized breccia bodies that are the focus of most of the work to date, including some mention of the Invermay zone (see Minfile No. 092HSW 002), reported separately to Mindat:
“Three different types of mineralization are found at the Giant Copper prospect. The first is tourmaline, sulphide, magnetite replacement bodies scattered throughout the Invermay stock and along its borders in adjacent Ladner Group metasediments. Alteration consists of the addition of fine-grained tourmaline and magnetite with lesser amounts of pyrite, pyrrhotite and chalcopyrite. Replacement zones frequently have an alteration halo of chlorite, sericite and actinolite.
The second type is lead-zinc-silver veins that form erratic lenses along northeast-trending structures. Mineralization consists of coarse sulphides in a gangue of quartz and calcite, enclosed in a strong fault gouge. [This is exemplified by the Invermay Mine, q.v.].
The third and most economically important type of mineralization is breccias with chalcopyrite, gold and silver mineralization. There are six known breccia bodies: the AM, Invermay, No. 1, Pass, Camp and New breccias. The Invermay breccia; however, is weakly mineralized and exploration in the area has concentrated on the Invermay vein. The Pass, Camp and New breccias have received only cursory exploration and have been previously considered lower priority exploration targets. The New breccia, located a couple hundred [sic - actually about 800 metres, see Assessment Report 36083] west-north west of the AM breccia, is described as an area of fractured and brecciated rocks with weak pyrite and trace chalcopyrite mineralization.
Breccia bodies consist of angular to sub-rounded fragments of sedimentary and mafic intrusive rocks in a matrix of calcite, quartz, tourmaline and feldspar. Sulphide minerals occur in patches and consist predominantly of pyrite, pyrrhotite, chalcopyrite and arsenopyrite with lesser sphalerite and galena and minor amounts of molybdenite, scheelite and magnetite.
The AM ore-body is an elongate, northwest- trending, series of sub-vertical plunging, breccia bodies bounded by steeply dipping faults. It has been the focus of the greatest proportion of exploration and has been subdivided into three sectors: the Northern Nose, Southern Nose and Central zones. The bulk of previously stated mineral resources are concentrated in and adjacent to a vertically plunging, crescent or horseshoe-shaped body of higher grade mineralization in the North Nose zone, which wraps around the northwest nose of the breccia. The east limb of the North Nose zone is open to depth below 15 level and the west limb is open to depth below 10 level. Several post mineralization northeast-trending faults cut the breccia. Diamond drilling in 1995 was successful in tracing a near- surface, northeast- trending breccia zone with copper mineralization in the southeast portion of the AM breccia. The Giant fault offsets the southeast part of the breccia 300 metres to the northeast. Mineralization occurs in a pipe-like zone of brecciated siliceous sediments. The zone measures 550 by 360 by 120 metres and comprises siliceous fragments in a grey matrix.
In the North and South Nose zones, mineralization consists of pyrrhotite, chalcopyrite and lesser pyrite as pockets in the matrix adjacent to fragments, and subordinately as veinlets cutting both matrix and fragments. Other minerals include arsenopyrite, molybdenite, magnetite, galena, sphalerite, uraninite, monazite and scheelite. The amount of sulphide minerals is not associated with the degree of brecciation. Where copper mineralization is weak to moderate, pyrite or pyrrhotite are the dominant sulphides. Strong copper mineralization areas are dominated by chalcopyrite as large blebs and clots rimming breccia fragments and partially filling the breccia matrix. These areas of strong chalcopyrite are accompanied by strong sericite clay alteration of the feldspathic breccia matrix or chloritization of an andesitic matrix. Zones of intense tourmaline alteration are commonly found immediately adjacent to, but postdate, zones of strong chalcopyrite mineralization. Copper-silver values within the AM breccia show a marked correlation while high gold values correlate with high copper values or elevated arsenic values; however, recent drilling has outlined several high- grade gold zones that are associated low copper values. The final 24.4 metres in drill hole GCR89-27 averaged 1.45 grams per tonne gold and 0.19 per cent copper (Assessment Report 24157). The uraninite is spatially associated with the molybdenite. The breccia matrix is composed of calcite, quartz, chlorite, carbonate, alkali feldspar, white mica and kaolin. Tourmaline occurs in fractures, fragments and the matrix. Mineralization in the central zone appears to be substantially lower in grade and lacking continuity.”

Comments by Giles Peatfield regarding some of the minerals reported:
Actinolite: This was reported by Wilton and Pfuetzenreuter (1990) as occurring in the matrix of the AM breccia body.
Amphibole: Amphibole minerals have been reported as hornblende (White, 1950), “pargasite” (Bacon, 1955), “basaltic hornblende” or “lamprobolite” (Campbell, 1965 and Waterland & Eastwood, 1969).
Ankerite: This was described by Waterland and Eastwood (1969) is lenses with quartz and calcite within hornblendite intrusions in the breccia body.
Antigorite: This was reported by White (1950) as an alteration product, probably of hornblende, and by Waterland and Eastwood (1969), in what they described as possibly an intensely altered mafic feldspar porphyry.
Apatite: This was reported only by Bysterbosch (1951) in this section, as “. . . large, euhedral crystals replaced to some extent by calcite and sulphides.”
Axinite: This was reported by Adamson (1957), in sedimentary rocks surrounding the breccia body, and by Campbell (1965) within the breccia body.
Biotite: Waterland and Eastwood (1969) reported that “In another [thin section] the lamprobolite (sic) was crowded with inclusions of deeply coloured biotite.”
Bornite: This was reported only by Bysterbosch (1951) as ex-solution particles not over 10 microns in size, in chalcopyrite.
Chlorite: This is common in the deposit; Bacon (1955) reported that some of the material in the matrix of the breccia is what he called “. . . a rare iron-rich variety, thuringite.”
Covellite: This was reported by Campbell (1965) as a minor alteration product of chalcopyrite.
Garnet: Campbell described “grossularite” but gave no detailed data regarding specific identification.
Gold: This was reported only by Bysterbosch (1951) as small particles (10 to 40 microns) as ex-solution bodies in chalcopyrite; in one case “The colour of this lath is slightly paler than that of pure gold.” which led him to propose “electrum”.
Hematite: This was reported only by Bysterbosch (1951), who stated it was common in the breccia matrix. It is interesting that none of the other workers mentioned this mineral.
Kaolinite: This was reported by Bacon (1955) as “kaolin”, as an alteration mineral.
Monazite: Bacon (1955), in a footnote to a table, reported that “Uraninite and minute amounts of monazite were identified in samples sent to the Department of Mines and Technical Surveys, Ottawa.”
Muscovite: This was reported only by Waterland and Eastwood (1969) in the matrix of the breccia.
Orthoclase: Bysterbosch (1951) reported a feldspar that he regarded as “apparently” orthoclase; Bacon (1955) described “alkali feldspar”. No-one has published a definitive identification, and the mineral should be regarded as tentative here.
Plagioclase: Bacon (1955) reported a plagioclase with composition about An50.
Pyroxene: McKechnie (1960) reported pyroxene, but gave no details, so the particular species is uncertain.
Scheelite: This was reported by Bacon (1955), and the reference was repeated by McKechnie (1960) and by Eastwood (1966), but I can find no independent confirmation.
Sericite: This was reported by Bacon (1955) and reiterated by McKechnie (1960) as “white mica”. I would regard it as valid for the locality.
Siderite: Waterland and Eastwood (1969) in describing a coarse breccia in one area of the deposit, mentioned that “Both the matrix and the fragments contain masses of pleochroic siderite 1 to 4 mm. across.”
Uraninite: Bacon (1955), in a footnote to a table, reported that “Uraninite and minute amounts of monazite were identified in samples sent to the Department of Mines and Technical Surveys, Ottawa.”

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Link to British Columbia Minfile:	092HSW001

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