Hornsby Quarry is a former blue metal quarry in Old Mans Valley at Hornsby, New South Wales, worked for dolerite. Hornsby Quarries Ltd, lessee of part of Norman Higgins' land in the valley, was installing plant by August 1913 and supplying metal by March 1914. The quarry cut into the volcanic neck of the Jurassic Hornsby Diatreme, exposing a cross-section more than 100 metres deep. The photographs, from 2015, show the crushing plant's conveyors, stairs and control desk, and the benched void.
By February 1914 the quarry had a suction gas plant and an inclined plane trolley-way to haul metal from the quarry to the top of the valley at Mount Errington. In March Hornsby Quarries Ltd advertised metal in standard sizes for immediate delivery, with special quotations for quantities over 100 tons a week.
Hornsby Road Metal Ltd was registered in November 1924 to acquire a contract for the quarry lease. It resolved to wind up in March 1932, yet in liquidation it supplied the Shire of Hornsby with blue metal under tenders accepted in 1935 and 1936. Hornsby Shire Council later bought the lease and machinery from the Higgins Estate, and in January 1953 called tenders to sell the lease of the Hornsby Blue Metal Quarry. Farley and Lewers worked the quarry from 1959. CSR, the owner by 2001, carried on operations there as a blue metal quarry.
In March 2001 CSR, relying on the land's open space zoning, required the Council to acquire it, and on 25 October 2002 Hornsby Shire Council compulsorily acquired Hornsby Quarry. From mid 2017 to January 2019 more than one million cubic metres of NorthConnex tunnel spoil was placed in the quarry. The site is now Hornsby Park, parts of it still under construction. Its first stage, the Crusher Plant Precinct, opened on 28 March 2026 with a lookout over the former quarry. Hornsby Quarry is listed as Hornsby LEP 2013 item 538.
Cumberland Argus (9 August 1913), Semeniuk in Land (2022), Hornsby Shire Council v FCT (AAT 2008) and Hornsby Shire Council (28 March 2026)
