Economic Geology
Lignite

Lignite float has been noted at many places in the map-area but as it is
Tertiary lignite, occurring with soft Tertiary sediments, no good exposures were
seen.

North of Cheslatta Lake, 5 miles east of Tyee Butte, large blocks of car-
bonized wood, dull lignite, and a bright, light-weight, waxy ‘coal’ were found
in a creek bottom. The material was not in place but had not travelled far. The
blocks were of a size to indicate a minimum seam thickness of a foot. The mater-
ial was compact when found but on drying the lignite broke into rectangular
fragments and the ‘coal’ broke with a conchoidal fracture. The extent, quality, or
origin of this lignite is unknown but it is believed to be Tertiary, probably as
late as Oligocene.

Along Nechako River north of Kenney Dam large blocks of lignite are strewn
along the exposed river bottom, but a careful search failed to disclose their source.
Dawson (1878, p. 82) reported a 4-foot seam along Nechako River near Mount
Greer but this was not seen—possibly is no longer exposed. The blocks were
sufficiently large to suggest that such a seam does exist. In all probability the
lignite is inter-basalt or is from the base of the plateau basalts and hence of late
Tertiary age.

Along Tsacha Lake, in Batnuni Valley, and along Chedakuz Valley small
fragments of lignite and fossil wood were noted. The source was not seen but the
fragments resemble previously described lignite. Possibly these too are derived
from concealed lignite beds in or beneath the Endako Group.

Hydrocarbons

A black hydrocarbon was noted in rhyolite 14 miles east of Batnuni Cone,
and another 2 miles south of the west end of Batnuni Lake on Swede Creek. It
occurs in vugs and cavities and in small fractures as a black, dull, tar-like sub-
stance. In places the material is brittle and has a conchoidal fracture.

A sample from near Batnuni Cone was examined by D. S. Montgomery,
Fuels Division, Mines Branch who reported that: “The hydrocarbon material in
the vugs is a native asphalt, which closely resembles liverite but is not identical
with this substance.”

Pumice and Diatomite

In 1876 Dawson (1878, p. 79) described an occurrence of pumice and
diatomite in a section of Tertiary sediments on the south side of Tsacha Lake.
The occurrence was exposed in a creek that enters the lake 13 miles from the
southwest end. The sediments underlie plateau basalts that occur on the flat
upland to the south. The creek has cut through the basalt exposing the sediments,
immediately below the basalts. They consist of grey fragments of pumice in a

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