The Henry fluorite showing is situated in the Gem 27 claim, 500 metres east of Mould Creek, 3 kilometres north of the settlement of Liard River on the Alaska Highway (Assessment Report 3975, Maps 4, 20), in one of the most important areas of fluorite mineralization in British Columbia.

The region is underlain by Lower to Upper Paleozoic, platformal sedimentary rocks of Ancestral North America (Geological Survey of Canada Maps 46-1962, 1712A, 1713A). The Henry showing is one of many similar fluorite deposits in a 17-kilometre long belt extending north from Liard Hot Springs Provincial Park. This belt is defined by an open anticline, with a gently south-plunging axis, in the Upper Devonian Besa River Formation, with the Middle Devonian Dunedin Formation exposed in a several-kilometre wide zone in the core of the fold. All the fluorite deposits in the belt are situated at or just above or below the unconformity between these units.

The Dunedin Formation consists of mid- to dark grey, massive to thinly-bedded fossiliferous limestone. It is generally exposed in the Teeter and Mould creek valleys, which are characterized by karst and 'mesa and butte' topography. The overlying Besa River Formation is predominantly black shale or slate and argillite, with some calcareous shale and minor, buff-brown dolomitic layers. The unconformity between the units is characterized by brecciation and is very irregular in detail, probably due to an erosional or disconformable relationship between them, or to later faulting along the contact (Assessment Report 3975). The mineral deposits in the Liard fluorite belt generally consist of lenticular replacement bodies or infillings in breccias in one or both units.

The Henry occurrence is near the crest of an anticline, possibly the main anticline referred to above, which is visible in limestone cliffs along strike to the south (Assessment Report 3975). It is just east of the hinge, and bedding dips gently to the east or southeast. No Besa River shale is present, and most of the outcrop comprises Dunedin Formation limestone, some with erratic patches or stringers of fluorite and barytocalcite.

Within the limestone are a few small areas of very strong replacement mineralization consisting of fluorite, witherite and calcite. The thickness of mineralization is generally around 6 metres, and the grades are good, but the zones appear to be of limited extent. In the best zone, 30 metres across in the north of the showing, three 6-metre long chip samples ranged from 13.7 to 44.9 per cent CaF2 (Assessment Report 3975, Map 20). Another zone to the south, 20 by 12 metres, contained similar values, including 52.4 per cent CaF2 over 5.5 metres (Assessment Report 3975, Map 20).

Fission-track studies of fluorite from the Gem prospect, 3 kilometres to the south, suggest that the age of the mineralization in the region is Mississippian (Open File 1992-16).

See the Gem (MINFILE 094B 002) occurrence for a completed work and exploration history of the area.