The Mayook Quarry 94 prospect consists of seven claims located to the south of the Canadian Pacific Railway, east of Mayook Station, 26 kilometres east of Cranbrook. Gypsum, known since before 1926, is exposed in four outcrops over an area measuring 800 by 300 metres. Three small test quarries have been opened on Lot 10220 and 10219. The prospect is probably a strike extension of the Sunrise prospect (082GSW045) to the north, although the intervening ground is heavily drift covered and no outcrop exposures are reported.

Most gypsum deposits in southeastern British Columbia are Devonian and/or Lower Carboniferous in age and this gypsum is thought to be hosted by Upper Devonian limestones of the Palliser Formation. The limestones strike generally north and dip steeply about 70 degrees east.

The gypsum is conformable with limestones to the east and west. The exposures, highly weathered and decomposed, are typically pale grey to grey and sucrosic. Bedding is indistinct except to the south where it dips steeply to the east. Locally, the gypsum is distinctly conglomeratic or brecciated, containing fragments of both gypsum and limestone.

The quality of the gypsum is consistently 77 per cent. An analysis indicated 28 to 30 per cent CaO, 5 to 6 per cent MgO, 0.5 to 1.4 per cent Fe2O3 plus Al2O3, 33 per cent SO3 and 16 to 17 per cent loss on ignition (Open File 1988-14).

In 1946, the Western Gypsum Company shipped 6950 tonnes to its Calgary plant, but no production has been reported since then.