The FSJ limestones are part of the Lower Pennsylvanian to Middle Triassic Pope Succession of the Cache Creek Complex.

The area is underlain by a north to south sequence of limestones, greenstones, and argillites. The northernmost limestones consist of massive to medium bedded, light grey weathering, tan to dark brownish grey granular, crinoidal limestone. A strike of 117 degrees and dip 48 degrees north was measured. These limestones are in contact with a 250 meter wide sequence of massive, blocky, strongly jointed greenstones which forms a south facing ridge across the original FSJ claims. The greenstones are in contact with a ridge of limestones to the south which is from 35 to 80 meters wide. These rocks are massive to rubbly, light grey weathering, granular, brownish grey limestones. A strike of 118 degrees and dip 36 degrees north was measured.

Prospecting for limestone was carried out in the region in 1989 by Continental Gold Corp which led to the staking of the FSJ 1-7 claims. In 1990, Continental Gold Corp. had A.M.S.Clark of Reliance Geological Services Inc calculate the volume and tonnage for the limestone, assuming that quarrying will go no deeper than the lowest outcrop of the limestone occurrence and no further into the hillside than the northern outcrop boundary of each occurrence.

Calculations were for the area within the 1990 claim boundary only and outside the Fort St. James municipal district. For the northern area a volume of 1,014,400 cubic meters and a tonnage of 2,749,024 tonnes was estimated; and for the southern area a volume of 434,000 cubic meters and a tonnage of 1,176,140 tonnes was estimated (Assessment Report 20231). The volume and tonnage figures are considered to be estimates based on assumptions that had to be made as to what was “available” limestone and are not geological reserves. These estimates are not compliant with NI43-101 standards.