The Knight Inlet quarry is located on the north shore of Knight Inlet, approximately 250 kilometres northeast of Vancouver. The quarry is within the Matsiu Valley of Matsiu Creek and produced monumental and ornamental stone known locally as Catherine Blue Granite.

The area is underlain by Jurassic to Tertiary Coast Plutonic Complex rocks.

Locally, a hornblende-diorite is medium-grained (1 to 5 millimetres) and has an attractive blue-grey tone that is darkened by euhedral phenocrysts of hornblende and blades of biotite. The groundmass consists of light blue-grey plagioclase and minor epidote. The contrast between felsic and mafic minerals is sharp and attractive, particularly when surfaces are polished, although occasional pitting and blind spots develop when slabs are polished. The rock is generally free of stains or knots but darkens along outcrop over a 40- metre interval south of the worked face. The worked face is 24 metres long by 2.4 metres high and is developed along a prominent set of vertical north-northeast striking joints. A second set of joints dips moderately to steeply southwest and strikes northeast. Joint and fracture density surveys indicate 35 per cent of joints are spaced greater than 100 centimetres apart.

Seven diamond drill holes, totalling 145.4 metres, have delineated 62 ,500 cubic metres of unaltered hornblende diorite. There is good potential for additional reserves of stone east of the worked face in an area covered by thin overburden (Fieldwork, 1987).

Princess Copper Mining Company drove adits on sulphide mineralization on the property prior to 1920. Four adits, totalling approximately 170 metres, were opened by Cambrian Copper Company in 1928.

Exploration on the marble was begun in 1966 by BBM Exploration. Knight Inlet Resources Limited was formed in 1969 to develop the marble potential of the property. Kellard Marble Inc. of Surrey operated the quarry on an experimental basis in 1985. The extensive fracturing found in samples removed from the quarry has limited further development. The company plans to outline less fractured reserves of stone before considering placing the deposit into production (R. Scheer, personal communication, 1991). In 1993, Barry Furneaux and Associates completed a program of prospecting and geological mapping. In 2012, Auracle Geospatial Science, on the behalf of S. Poystila, completed a satellite remote sensing survey and analysis on the area.