The slate deposits in Mintaro (South Australia)

The Mintaro Slate quarries, opened in 1856 in Mintaro Shale, are among the oldest continuous quarrying operations in Australia. Mintaro stone is well suited for paving, panelling, floor tiles and for high-quality slate in architectural work. Full size, single piece billiard tabletops are a specialty.

The slate of Mintaro is being mined in the Mintaro shale of the Belair Subgroup which is the upper part of the Neoproterozoic Burra Group within the Adelaide Geosyncline. Near Adelaide, the base of the Belair Subgroup begins with the coarse Sturtian arkose known as the Mitcham and Leasingham Quartzites and sharply overlies the Saddleworth Formation. This formation is supposed to be a sequence boundary and is transgressive upwards to laminated siltstone to which the Mintaro Shale.

Geological map and cross section (after Preiss, 2006).