The sandstone is notable for its geological characteristics; its relationship to Sydney's vegetation and topography; the history of the quarries that worked it; and the quality of the buildings and sculptures constructed from it.

One author describes Sydney's sandstone as "a kind of base note, an ever-present reminder of its Georgian beginnings and more ancient past.

"[4] Sydney sandstone was deposited in the Triassic Period probably in a freshwater delta and is the caprock which controls the erosion and scarp retreat of the Illawarra escarpment.

It is composed of very pure silica grains and a small amount of the iron mineral siderite in varying proportions, bound with a clay matrix.

Reporting on them in 1892, Professor Liversidge said "The Hawkesbury sandstone and Waianamatta shale was, of course, derived from older and probably gold-bearing rocks hence it was not unreasonable to expect to find gold in them.

"[11] The sandstone is the basis of the nutrient-poor soils found in Sydney that developed over millennia and 'came to nurture a brilliant and immensely diverse array of plants'.

Called on by the Colonial Architect, for example, to be used in the main buildings of the University of Sydney, the stone was supplied from the Pyrmont quarries where there were at least 22 quarrymen working by 1858.

The sculptor William Priestly MacIntosh, for example, carved ten of the explorers statues for the niches in the Lands Department building in "Pyrmont Freestone".

In 1908 questions were asked in the Legislative Assembly in the parliament of New South Wales about how likely the men cutting sandstone in Sydney were to contracting the disease and whether the Government should grant medical aid to them.

[29] The early administrators of the colony at Sydney Cove sent groups of prisoners to an area nearby, named The Rocks, to eke out what ever existence they could from the land and build housing for themselves.

[30]Demand for Pyrmont stone surged in the years following the gold rush when prosperity meant that many public and private buildings were constructed.

In 1909, for example, when an enquiry was undertaken about remodelling the Parliamentary Buildings in Macquarie Street it was reported that "the external work, excepting the southern flank, was to be carried out in Sydney sandstone and the main flight of steps in stone obtained from the Purgatory quarry".

The combination of slowing demand and technical difficulties forced quarries out of business,[35] although restorations and extensions of important public buildings still required Sydney sandstone.

One architect, Elias Duek-Cohen, referred to its material in his defence of the building: 'It has a fine facade in warm-coloured stone ... forming a richly modelled surface'.

It destroys habitat, alters landform, drainage and soil conditions, creates waste pollution, and usually generates noise and dust ...

[44] In spite of the shortages, the revived industry continues to quarry, process, and supply the stone for building, landscaping, commercial, and conservation work in Australia and there are public courses available in Stonemasonry.

[45] It is now also used as a contemporary building material in major constructions and restorations such as Governor Phillip Tower and the Commemorative Museum, winning international architectural awards for excellence.

Architects, such as the Robin Boyd Award winner Graham Jahn, describe Sydney's sandstone buildings as "wonderful".

[46] A small, highly skilled team of stonemasons responsible for maintaining Sydney's sandstone buildings was established early in the 1990s.

For example, in 2012, conservation work was done on the sandstone of the clock tower of Sydney Town Hall as part of a four-year, $32 million project to restore the building.

For example, the Royal Botanic Garden, Sydney commissioned sculptor Chris Booth to design a living sculpture (entitled Wurrungwuri) for its grounds, officially unveiled 9 March 2011.

One of the two main pieces of the sculpture is a 'sandstone wave', consisting of about 200 tonnes of sandstone blocks in an undulating form reminiscent of the tectonic forces that created the stone.