The Imperial Limestone quarry is located near the centre of Lot 500, 1.25 kilometres southwest of Spratt Bay near the north end of Texada Island. Limestone has been quarried here since 1951.

The quarry is developed near the eastern edge of a 13 kilometre long belt of Upper Triassic Vancouver Group, Quatsino Formation limestone up to 3 kilometres wide that is situated along the axis of a broad northwest plunging syncline. The limestone is produced from the lowest member of the Quatsino Formation, consisting of a 100 metre thick bed of exclusively high calcium limestone. Several steeply dipping, west striking faults are exposed in the quarry. A few hundred metres to the southwest the limestone is in fault contact with basaltic flows of the Karmutsen Formation.

The deposit consists of irregular masses of white limestone in black limestone, with gradational and sharp contacts separating the two types. Both types are fine-grained. Samples of randomly collected chips of white limestone (sample 1) and black limestone (sample 2) contained (Bulletin 40, page 79, Sample 1 & 2):

-----------------------------------------------------------

Sample 1 (values in per cent) Sample 2

CaO 54.7 54.9

MgO 0.47 0.36

Insolubles 0.78 0.68

R2O3 0.06 0.06

Fe2O3 0.04 0.11

MnO 0.003 0.002

P2O5 0.018 0.010

Sulphur 0.01 0.02

Ignition loss 43.6 43.7

H2O 0.12 0.12

------------------------------------------------------------

This deposit was initially quarried by Don McKay between 1951 and 1958. Imperial Limestone acquired the property in 1959 and has continued operating the quarry to the present day. Between 1952 and 1987, 4.56 million tonnes of limestone have been quarried. The majority of the current production is barged to Seattle.

Recent sampling by quarry personnel of sulphide mineralization, at the edge of the quarry, returned values in zinc, silver, lead, copper and gold (I. Webster, personal communication).