The Rosebank deposit is located on the west side of Esquimalt Harbour, 9 kilometres west of Victoria.

A band of limestone, 400 metres wide, extends westward from the shore of Esquimalt Harbour for at least 2 kilometres hosted within greenstone of the Wark Gneiss. The Wark Gneiss is possibly the metamorphic equivalent of a mafic unit of the Paleozoic Sicker Group, the latest metamorphism having taken place in the Jurassic. The limestone strikes 110 degrees and dips 70 degrees southwest to 70 degrees northeast. The limestone is extensively fractured and one distinct fracture cleavage strikes northwest and dips approximately 70 degrees northeast. Randomly orientated, greenish, mafic dykes a few centimetres to 15 metres wide are locally quite numerous.

The deposit is comprised of very fine-grained, dark bluish grey to nearly white limestone that commonly displays banding parallel to the fracture cleavage. Most of the limestone is high calcium in composition. Occasional patches and small masses of magnesian limestone occur along the margins of the band and along contacts with dykes. A sample from a quarry 900 metres from Esquimalt Harbour contained 54.70 per cent CaO, 0.60 per cent MgO, 1.08 per cent SiO2, 0.44 per cent Al2O3, 0.12 per cent Fe2O3 and 0.06 per cent sulphur (CANMET Report 811, page 142, Sample 1).

Between 1912 and 1933, 218,282 tonnes of limestone were quarried. In 1933, the plant was dismantled and the property was eventually acquired by the Department of National Defense.