The Midnight showing is located 3.4 klilometres south east of the community of Christina Lake.

The area is underlain by Carboniferous to Permian Mount Roberts Formation mudstone, siltstone and fine clastic sedimentary rocks that enclose the tectonically emplaced ‘Castle Mountain’ ultramafic body consisting of serpentinized dunite.

Small pods of chromite up to 3 metres in diameter occur in the ultramafic rocks. In 1986, a hand specimen of massive chromite ore taken from a dump analysed 58,918 parts per million chromium (Assessment Report 16358).

In 1986, Shangri-La Minerals Limited conducted a program of geological mapping, sampling, geochemistry, self-potential and ground and aerial magnetometer surveys on behalf of Nitro Resources Inc. over the Castle Project claims. In 1995-96, E. Alionis completed a ground magnetometer survey and a gechemical sample program consisting of soil and basal till sampling, and rock chip sampling. Rock chip samples returned 0.22 per cent nickel and 0.08 per cent chrome (Assessnent Report 24636)