The Indata Lake Mercury occurrence is situated on the east shore of Indata Lake near its outlet, approximately 49 kilometres southeast of Takla Landing. The area was explored for its mercury potential during the Second World War and again in the late 1960s.
The area is underlain by sediments assigned to the Carboniferous to Jurassic Cache Creek Complex in contact to the east with andesitic volcanics of the Middle Triassic to Lower Jurassic Takla Group along a north-northwesterly trending portion of the Pinchi fault zone. Locally, ultramafic masses formerly assigned to the Middle Permian to Late Triassic Trembleur intrusions and now termed Mississippian to Triassic Oceanic Ultramafites, have been emplaced in these rocks.
In the area of the occurrence, massive blue-grey coloured Cache Creek Complex limestone hosts local small dikes and sills of serpentine. On the east shore of Indata Lake, a brecciated fault zone, 3 to 6 metres wide, cuts the limestone. This zone strikes north, dips at 70 degrees to the west and has been traced 300 metres north from the lakeshore to where it becomes masked by overburden. A series of northeast-striking crossfaults appear to have offset the zone by up to 3 metres. At the north end, it follows the contact between a serpentine dike and limestone for 53 metres. Along the zone, the limestone has been altered to a buff-coloured carbonate and the serpentine dike has been brecciated and altered to a reddish buff-coloured ankeritic carbonate with local irregular chert fragments and green mica (mariposite?). Stringers of magnesite and quartz up to 5 centimetres wide cut the altered dike. Most of the cinnabar mineralization occurs as widely scattered grains within the chert fragments, either in the dike or in the fault breccia, along calcite-filled fractures or within the interclastic matrix.
A 1.52-metre wide sample across the breccia zone near diamond-drill hole 2 assayed 0.84 kilogram mercury per tonne (0.084 per cent) (Assessment Report 1236, page 3). Traces of cinnabar in cemented volcanic breccia with minor mariposite, showed up in only one of seven holes drilled along the structure.
