Princeton Coal is located about 0.5 kilometre southwest of Allison Creek and 5.5 kilometres north of Princeton.
This coal deposit is situated in the north-central part of the Princeton Basin, a northerly trending half-graben superimposed on volcanics and sediments of the Upper Triassic Nicola Group. The basin is separated into a northern and southern area by the gentle, northwest-trending Rainbow Lake anticline. The northern area, in which this deposit occurs, consists of a gently folded homoclinal panel, with dips ranging from 15 to 25 degrees.
Princeton Coal is hosted in a sequence of sandstone, shale, waterlain rhyolite tephra (tuff) and coal, up to 2000 metres thick, comprising the Eocene Allenby Formation (Princeton Group). The more significant coal seams occur in a sequence of sandstone with lesser claystone, siltstone and mudstone, and minor grit. The seams are commonly overlain and underlain by carbonaceous mudstone or claystone containing abundant fossils.
One vertical drillhole (PC-1) intersected five significant coal seams 1.07 to 2.13 metres thick at depths of 36.6 to 51.1 metres. Six other vertical holes drilled to the east, west and south, within 400 metres of this hole, intersected thinner high-ash seams.
The coal is high-volatile bituminous C in rank (A.S.T.M. classification). The five coal seams vary from being dull, slightly muddy, and blocky to hard, shiny, and vitrain rich. Blebs of amber (resinite) are occasionally present. Samples from the five seams analysed 14.06 to 39.2 per cent fixed carbon, 27.81 to 51.51 per cent ash, 0.40 to 1.07 per cent sulphur, and 6172 to 9130 British Thermal Units per pound (dry basis) (Coal Assessment Report 195, core logs). Two of the better intersections analysed as follows (in per cent, dry basis) (Coal Assessment Report 195):
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Sample 1 Sample 2
Length (metres) 1.22 1.07
Volatile matter 37.58 39.20
Fixed carbon 38.59 49.21
Ash 27.81 29.28
Sulphur 0.88 0.40
Calorific value 9130 8868
(B.T.U.'s per pound)
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Sample 1 is of fairly pure coal with blebs of amber (hole PC-1, 37.5-38.7 metres). Sample 2 is of dull, black, blocky coal (hole PC-1, 46.2-47.2 metres).
The general area was first drilled by Cominco Exploration, during a search for sediment-hosted uranium mineralization. This drilling intersected several thin coal seams. The coal-bearing sediments were then tested by a second series of four rotary holes totalling 351 metres in 1980 by Cominco and Fording Coal Ltd. Cominco drilled an additional 7 holes totalling 537 metres in 1981.
