The San Pedro Quarry is accessed by taking the North Forks road from the community of Grand Forks to the Brown Creek road. Then travel 23.5 kilometres up the Pass Creek Road and turn left (west) on a spur road for 2 kilometres.
The gabbro was discovered in 1992. In 1993, Western Canadian Quartzite Ltd. and San Pedro Stone Inc. requested 5 diamond drill holes, totalling 121.9 metres. The 1995 proposed work includes trenching and fresh rock sampling by benching of a rock outcrop area. The stone is being shipped to Korea (Information Circular 1996-1, page 10). A new (1996) plant in Squamish, operated by Garibaldi Granite Group and Pender Capital Corporation, will process stone from this quarry.
A small group of outcrops, of coarse-grained gabbro, along a logging road lead to stripping and test quarrying which has exposed the gabbro over a 30 by 50 metre area. The stone has a moderate, irregular fracture pattern which allows quarrying of commercial sized blocks with estimated waste of up to 50 percent. The stone is uniform without any foreign rock inclusions. It may be part of a Jurassic Nelson Plutonic suite pendant in a Eocene Coryell Intrusion syenite pluton.
The stone is a uniform, dark black with a slight greenish cast, medium-grained gabbro. Major constituents are plagioclase, clinopyroxene (augite) and biotite. Minor constituents are orthoclase, chlorite, apatite, magnetite and pyrite (1 per cent). The mafic minerals are slightly altered to chlorite, plagioclase is slightly albitized and pyrite is fresh. There is no quartz. The rock takes an excellent, bright, glassy, polish (9/10) with very minor pitting at mafic minerals. The rock looks fresh with no visible alteration, staining or fabric. There are a few, tight cracks, typically 1 to 3 centimetres long.
San Pedro Stone Inc., a subsidiary of Garibaldi Granite, produces Pedro Black from this quarry. The quarry was mapped in 2015 (Assessment Report 35553). The area around the quarry was geologically mapped in 2016 also by Helgi Sigurgeirson (Assessment Report 36272).
