Black granite was quarried for building stone on the Canadian Pacific Railway near Coryell, 14 kilometres northeast of the south end of Christina Lake.

The quarry is developed in the Middle Eocene Coryell batholith near its northwestern margin. This intrusive body is comprised of a core of light reddish to brownish pink, medium to coarse grained hornblende-biotite pulaskite that is enclosed in a more mafic marginal phase.

The stone is described as a coarse grained augite-biotite- hornblende monzonite that exhibits white minerals up to 12 milimetres in diameter together with jet black and greenish minerals arranged in a gneissic manner. In thin section the rock consists of orthoclase, andesine, microperthite, biotite, diopside partly altered to greenish hornblende and a few grains of magnetite. Overall the stone is of fairly uniform grain size and displays a dark speckled appearance on cut surfaces. The stone is occasionally feldspar porphyritic and sometimes marred by fine light stringers.

Jointing at the quarry is extensive. An ill-defined and discontinuous sheeting, dipping 30 degrees west, towards the railway tracks, is cut by a vertical dipping joint set striking 020 degrees and numerous other irregular cross joints. Large blocks of stone can still be recovered in places at the quarry despite the stone being so badly shattered. Physical properties are as follows (Parks, 1917, page 121):

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            Specific gravity                       2.901
            Crushing strength (dry) (lbs/sq.in.)  23,291
            Transverse strength (lbs/sq.in.)       2,278
            Shearing strength  (lbs/sq.in.)        2,752
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The quarry was operated by the Canadian Pacific Railway in the early 1900's, supplying building stone for the construction of retaining walls, culverts, tunnels and bridge piers along the railway between Midway and Nelson. The stone was also used for structural purposes in Grand Forks and Greenwood, such as in the Greenwood Post Office. No production figures are available.