Come By Chance – Gold-Copper
Breccia, Porphyry, Epithermal Modelling
- The Come By Chance Conceptual Model indicates the presence of a large system demonstrated by numerous pits and adits throughout the property particularly
Cu-Au-Ag skarns along NW trending fault zones.
- Extensive brecciation near the Browns Pit along with a magnetic low flanked by strong magnetic high anomalies may be evidence of a breccia pipe with a suspected link to an underlying porphyry.
- “Presence of well mineralized copper bearing monzonite potentially displaying a porphyry/skarn linkage in SE Betts area are indications of porphyry potential in the monzonites.” (Graeme Evans, Teck Cominco, 2006 property inspection).
The CBC property is comprised of 21 mineral claims as well as 15 reverted crown granted mineral claims covering an area of approximately 527 hectares (ha). The claims are situated about 8 kilometres (km) northwest of the city of Grand Forks, B.C. and 3kms south east of the former Phoenix Mine which produced during the period 1900 – 1976, 27 million tonnes at a grade of 0.9% Cu and 1.12 g/t Au, from a number of different ore bodies (Church, 1986). This amounts to over 1 million ounces of gold and 500 million pounds of copper produced from the Phoenix deposit.
The CBC property covers stratigraphy prospective for both copper gold skarn and auriferous volcanogenic massive sulfide-oxide mineralization. In addition, the structural setting of the property is favourable for epithermal gold mineralization. Indications of each of these three styles of mineralization occur on the property, which is situated in a region with a long history of mining and with significant past gold production from deposits representing each of these styles of mineralization.
The CBC property has not been systematically explored. Exploration to date has focused largely on copper skarn type mineralization similar to that at the nearby Phoenix deposit.
The majority of the early work was at the Betts showing (Minfile 082ESE261), in the southern part of the CBC property. The Minister of Mines Annual Report for 1904 and 1905 documents some 208 feet of open cuts and shallow shafts at the Betts, as well as a 75 foot long (upper) tunnel with a 40 foot winze and an 825 foot (lower) tunnel. This lower tunnel was driven to cut the mineralized zone 375 feet below surface. A chute of massive pyrrhotite ore was reportedly intersected at a distance of 575 feet in the lower tunnel.
Epithermal style of mineralization is under-explored on the claims and given the regional importance of epithermal gold mineralization and the favourable structural setting, a thorough exploration program to assess the property for this style of mineralization is planned. In particular the area around the CBC 98-1 drill hole situated about 100 meters southeast of the lower Betts adit and close to, and in the footwall of the Eagle Mountain Fault which intersected epithermal quartz veins and quartz flooding with associated sericite alteration, to try to find the surface expression of the epithermal system seen in the drill hole.
Evidence of extensive brecciation near the Browns Pit along with a magnetic low flanked by strong magnetic high anomalies may be indications of a breccia pipe with a suspected link to an underlying porphyry.
Porphyry phases may be defined by Magnetic Lows flanked by local, intense highs associated with skarns and intermediate volcanics.
Magnetic lows may be associated with the mineralized zones where original magnetite is destroyed by the alteration.
Graeme Evans of Teck Cominco noted in a 2006 property inspection “numerous showings are present through the Brooklyn sequence and generally consist of Cu-Ag-Au skarns along main faults within several rock types.
These are isolated occurrences of a large system demonstrated by numerous pits and adits throughout the property particularly along NW trending fault zones. These fault zones display widths up to 100 meters and consist from W to E of the Eagle Mtn. Fault, the Central Hardy Mtn. Fault and the eastern Lind Creek Fault thrust often associated with ultramafic slices reflecting strong fault emplacement. The sequence in the area is dominated by mafic volcanics of the limestones of the Triassac Brooklyn and sharpstone sequence are commonly seen with shallow dips in a possible broad antiform. Mineralization is dominated by variable amounts of pyrrhotite and chalcopyrite in both massive garnet skarn and calcsilicates in mafic volcanics.
There are indications of porphyry potential in the monzonites. An encouraging feature is the presence of well mineralized copper bearing monzonite potentially displaying a porphyry/skarn linkage in SE Betts area.
The Greenwood Mining Camp
Come By Chance Claim Map
Mag low flanked by intense Mag highs
Conceptual Model for Styles of Epithermal Gold-Silver, Breccia and Porphyry Copper Mineralization
The angular and sub-angular breccia fragments with rounded breccia fragments indicate an initial dynamic breccia created by the movements along the faults with subsequent hydrothermal breccias within the structures.
The brecciated quartz veins indicate the iron content was derived from metamorphism caused by the quartz intrusion; although the iron may have been emplaced at various stages.