Heatherlie quarry is of historical, scientific (technical) and social significance at the State level. The quarry provided the first really durable freestone (sandstone) discovered in Victoria and its development exemplifies the technical, political and social problems associated with isolated industrial locations in the State. It remains today as the most complete illustration of quarrying methods for cut stone. Its north end has a sheer raking face and examples of partly extracted blocks which retain evidence of the traditional wedge and feather technique. Associated buildings, structures, approach and on-site railway workings plus machinery relics, provide insights into the infractructure essential to any major quarrying operation.
The quarry is also of historical significance for its involvement, from 1882 onwards, with the supply of stone for Parliament House Melbourne. The selection of the stone for Parliament House was the basis of protracted contorversy regarding the relative quality and durability of Victorian compared with imported stone. Other notable uses of the stone include buildings at Stawell, such as the Court House of 1878-9, which was the government's first experiment in using the stone and the town hall designed by John D'alton, and built in 1872-3, using the freestone only for the dressings.
The cottages on the site are an excellent representation of the use of the stone in a vernacular fashion and must be regarded as part of the site.
The survival of substantial pieces of machinery contributes to the significance of the site. The railway line from Stawell is significant as a Government built branch-line to a privately operated quarry and retains remnants of unique timber bridge structures.