Quartzite is quarried for flagstone on the Keith claim at the headwaters of Porcupine Creek, 19 kilometres northeast of Salmo.

This area is underlain by a sequence of metamorphosed carbonates and clastic sediments of Lower Paleozoic age. These rocks have been folded into a series of north trending anticlines and synclines that have steep to near vertical limbs.

The quarried stone is quartzite, with some interbedded schist, marble, argillaceous quartzite and conglomerate of the Lower Cambrian Quartzite Range Formation (correlative with rocks of the Hamill Group). These beds strike north and dip 80 to 84 degrees west. Jointing of moderate intensity is developed perpendicular to bedding. Individual quartzite beds display various colours including white, blue, pink, golden, brown and green. Only the top 6 metres of the deposit is quarried because of an undesirable colour change below this depth. Well developed micaceous partings enable the quartzite to be split into layers as thin as 1.3 centimetres. This flagstone is reported to be of excellent quality with good tooling characteristics (A. Gerun, personal communication, 1991).

Quartzite has been quarried here since 1978. The deposit is currently being operated on a seasonal basis (1 to 2 months per year) by Gerex Developments Ltd. of Nelson. The stone is hand split along micaceous partings to produce flagstone of variable thickness. Thin flagstone (up to 5 centimetres thick) is sold for building facings, patio walkways and fireplaces. Thicker flagstone (wallrock) is used in the construction of retaining walls. Some material is also crushed for aggregate. Annually, 500 to 1000 tonnes of flagstone are produced and sold throughout western Canada by Gerex Developments (A. Gerun, personal communication, 1991).