A limestone lens of the Middle Triassic Brooklyn Formation outcrops on Highway 3, 3.5 kilometres due south of Eholt and continues south-southwest for 1.75 kilometres to the Phoenix Road, 1.6 kilometres west-northwest of the road's conjunction with the highway. The limestone strikes 002 degrees and dips 65 degrees east at the highway outcrop on the north end of the deposit.

The lens is comprised mostly of light grey to white, fine grained limestone with some black to dark grey limestone. Scattered thin, cherty and argillaceous beds occur within the limestone. Streaks of disseminated pyrite are sometimes present. The limestone is intruded by numerous sills and dykes. A sample from an exposure along an old railroad, 800 metres south of the Oro Denoro Mine (82ESE 063), just west of the highway , contained 51.39 per cent CaO, 0.67 per cent MgO, 5.70 per cent SiO2, 0.42 per cent Al2O3, 0.39 per cent Fe2O3 and 0.04 per cent sulphur (Canmet Report 811, p. 202, Sample 60).

A second, 2 kilometre long, subparallel lens of mostly white, medium grained limestone outcrops 500 to 900 metres west of the first lens. Some chert beds and dykes are present within this lens. A sample of chips taken across 90 metres on top of a knoll, 2.5 kilometres northwest of the Phoenix Road-Highway 3 conjunction, contained 48.47 per cent CaO, 0.70 per cent MgO, 11.20 per cent insolubles, 1.04 per cent R2O3, 0.74 per cent Fe2O3, 0.04 per cent MnO, 0.13 per cent P2O5, 0.02 per cent sulphur 38.69 per cent ignition loss and 0.28 per cent water (Minister of Mines Annual Report 1960, p. 143, Sample 6).