Red Chris is 70% owned by Newcrest Red Chris Mining Limited, a Newmont subsidiary, and 30% owned by Red Chris Development Company Ltd., an Imperial Metals subsidiary.
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Summary:
Gold and copper porphyry-style mineralization consists of vein, disseminated and breccia sulfides. The main sulfide mineral assemblage is pyrite-chalcopyrite-bornite.
Red Chris is in the Iskut district, on the northern edge of the Skeena Mountains. Most of the property is situated on the Todagin Upland plateau. The Red Chris deposit on the southern edge of the plateau is hosted by the Red stock, which was emplaced in the very Late Triassic into deformed Stuhini Group sedimentary and volcanic rocks. Lower Hazelton Group volcanic and sub-volcanic rocks, similar in age to the Red stock, dominate the western part of the Todagin plateau, unconformably overlying Stuhini Group. Post-mineralization erosion during the Early Jurassic was followed by deposition of mainly sedimentary upper Hazelton Group rocks, and the succeeding Bowser Lake Group in the Middle Jurassic; these units originally covered the partly eroded Red stock and Stuhini Group, but they are now preserved only along the southern margin of the plateau due to southeastward tilting in the Late Cretaceous.
The Red stock is an ENE-elongate intrusive complex up to 8 km long by 1.5 km wide at surface. It consists of a series of porphyries beginning with pre-mineral leucodiorite, which forms the bulk of the complex. This was intruded by quartz monzonite porphyries which were coincident with potassic alteration and quartz vein-hosted copper-gold mineralization. Finally, late and post-mineralization porphyries and dikes were intruded. The current Red Chris ore reserve, where open pit mining is ongoing, consists of the East Zone and the Main Zone each of which contain pods or clusters of copper- gold ore centred on the mineralizing porphyries. At surface, combined East Zone and Main Zone mineralization extends about 2,000 m along the stock’s east-northeast axis; in width, it ranges from at least 100 m in the East Zone to 650 m in the Main Zone. The depth of significant mineralization is over 1,200 m in the East Zone and about 1,000 m in the centre of the Main Zone. A further 1.5 km to the west of the open pit are the Gully and Far West exploration Zones, which have similar geological characteristics to the East and Main Zones. The Gully Zone footprint is approximately 400-500 m across, east-west. The Far West Zone has a smaller footprint and has seen less drilling than the other zones. The new East Ridge Zone several hundred metres east of the East Zone extends the known mineralized corridor at Red Chris to approximately 4 kilometres.
Mineralization consists of thin wavy or thicker planar quartz veins and stockworks containing chalcopyrite, bornite and magnetite; these minerals are also disseminated outside the veins. In the upper part of the ore deposit, potassic alteration is rarely preserved and the rocks are dominated by sericite-pyrite and clay-carbonate-hematite overprinting alterations; here, chalcopyrite and pyrite are the dominant sulfides, with bornite best preserved in the core of the East Zone. Gold occurs as microscopic inclusions in the copper sulfides. Molybdenite occurs locally in quartz veins, especially deeper and outside the high-grade core. The Red Chris deposit has been modified by syn-to post- mineralization faulting, including the Late Cretaceous South Boundary fault.
Red Chris is a typical porphyry copper deposit based on the composition of its host rocks, its alteration pattern and sequence, and its ore mineralogy. It may be classified as belonging to the high- potassium calc-alkalic type of porphyry system, which includes several world-class deposits such as Bingham (Utah).