Latitude -32.416667, Longitude 152.216667
Located in the Mid North Coast Region of NSW, nearest town Bulahdelah
Bulahdelah Mountain lies to the east of Bulahdelah township and dominates the Myall River floodplain at its base. This mountain is significant to the local Worimi Aboriginal people who call it Bulla Della, meaning 'the Great Rock'. The mountain, a volcanic extrusion, is also known as Alum Mountain, after a rare alunite deposit was discovered there in the late 1800s and subsequently mined until 1952. In 1917, this alunite deposit was reported as one of only 3 known deposits in Australia and the largest deposit in the world.
There are 3 units in the Early Permian Alum Mountain Volcanics at Bulahdelah Mountain - Sams Road Rhyolite which consists of ignimbrite, lava flows, tuff and breccia that has been variably altered by hydrothermal fluids; Markwell Coal Measures, high grade coal interbedded with carbonaceous shale, fine grained sandstone and conglomerate; Burdekins Gap Basalt, an olivine basalt that may range from slightly weathered and strong, to the (more common) highly weathered and plastic clay associated.
Alunite varies in colour from white to yellow gray. The mineral is a hydrated aluminium potassium sulphate and occurs as veins and replacement masses in trachyte, rhyolite, and similar potassium-rich volcanic rocks. It is formed by the action of sulphuric acid bearing solutions on rocks during the oxidation and leaching of metal sulphide deposits.
The Australian Alum Company took up the first mining lease on Alum Mountain in 1888 and in 1890 works were established at Bulahdelah for the production of alum and aluminium sulphate. Local consumption in Australia for alum was too small so the company exported the material to Liverpool, England.
The mined alunite was sent by an incline tramline to bins on the bank of the Myall River, transported by steam punts to Port Stephens, and from there, conveyed to Sydney by steamer, to be shipped in bulk overseas. Quarry sites and ruins of the mining and transport of alunite still remain on the mountain and can be seen via the trail which winds up the incline to the lookout at the top.
As well as the Alunite deposit and associated mining history at Bulahdelah Mountain, there are examples of rare orchids, particularly Rhizanthella Slateri, an orchid that flowers underground. Additionally, the track up the mountain is very scenic with many spectacular grasstrees and boulders adorning the slopes..
Bulahdelah township is located on the Pacific Highway, about 230km north of Sydney. Bulahdelah Mountain lies on the eastern side of the town and is accessed by Church Street, crossing the expressway and leading to Mountain Park, where the track to the mountain-top commences.