LOIS, LOIS 1-36, BOZO 1,4, HART LAKE
The Lois occurrence lies within the Insular Belt of the Cordillera, and is underlain by Upper Triassic tholeiitic basalts of the Karmutsen Formation (Vancouver Group). These have been intruded by a small quartz diorite stock of the Jurassic Island Plutonic Suite. The stock, called the Lois stock, is about 1.4 by 1.6 kilometres in area. Quartz diorite forms the outer portion of the complex and makes up more than half the rock present. The most widespread alteration is biotization and is common in all main rock types except the rhyolite breccia. In the main rhyolitie breccia, incipient argillic alteration has destroyed any primary or secondary biotite that may have been present in the original rhyolite. In the Southwest Margin rhyolite breccia, several diferrent alteration types occur over the 100-125 metre length of the outcrop. The most common type is quartz-carbonate accompanied by 2 to 4 per cent pyrite and trace chalcopyrite. The carbonate is siderite or ankerite with traces of mariposite or fuchsite. Argillic alteration similar to the alteration within the main rhyolite breccia is less common.
The occurrence encompasses several styles and locations of weak mineralization. Up to 5 per cent sulphides occur in the rhyolite breccia as disseminations with minor amounts occurring in fractures. Up to 3 per cent arsenopyrite is common in the main rhyolite breccia. This breccia also hosts disseminated black sphalerite in amounts up to 0.5 per cent. Galena is present in trace amounts. Erratic amounts of chalcopyrite and molybdenite occur in the biotite-altered zone of the intrusive rocks. Sphalerite and galena occur in rhyolite dykes on the Lois 15 claim (Assessment Report 2384). Unspecified cobalt mineralization is found on the Lois 5 claim's west corner. (extract from MINFILE 092L 330).
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