Coimadai Antimony Mine, Victoria

Coimadai (pronounced come-ida) Antimony mine is on Pyrete Creek, a tributary of Goodman’s Creek, about 15 km NNE of Bacchus Marsh. It consists of two lodes, Draper’s and Bondison’s. The deposits were discovered in 1887 and worked intermittently until 1915, then operated again between 1942 and 1944.

Featured image: John Carey on the Coimadai Mine dumps, June 2003.

The deposits occur in Lower Ordovician sandstones and slates. The lodes occur in fault zones in intensely sheared rock. Today, collecting is on the dumps and along the creek bed. Permission is required as the area is in a water catchment.

Antimony oxide minerals can be found on the dumps. No analyses is known and a number of species may occur.

One of the Coimadai Mine adits, June 2003.

The Minerals


Well-formed, but small, arsenopyrite crystals with stibnite in quartz, Coimadai Mine.


Gold occurred in the alloy aurostibite in the deep levels of the mine (Wightwick, 1999).


Yellow cervantite crystals (visual identification only). Reported by Anderson (1916).


Reported by Anderson (1916).


No data available. Probably a post-mining efflorescence.


White to cream crystalline balls occur rarely, originally reported as basaluminite, now known as felsőbányaite.


Occurred as rare grains in the ore (Fisher, 1943).


Free gold occurred in the upper levels of the mine (Wightwick, 1999).


George Lysiuk Collection – visually identified. Reported by Anderson (1916).


No data available.


Occurs in ore.


Quartz is the gangue mineral of the orebody.


No data available.


Silver prismatic stibnite crystals in quartz. Fisher (1952) reported that stibnite occurred as partly massive and fine-grained, and partly coarsely crystallised when associated with quartz.


Small pale yellow crystals as an alteration of stibnite.


Anderson, C. (1916), Bibliography of Australian Mineralogy, New South Wales Department of Mines, Mineral Resources No.22.

Fisher, N.H. (1943), Geological Report on the Coimadai Antimony Mine.

Fisher, N.H., (1952), The Coimadai Antimony Mine, in Edwards, A.B. (ed.) Geology of Australian Ore Deposits.

Wightwick, C. (1999), The geology of the Coimadai Sb-Au deposits, central Victoria, with emphasis on petrology and geochemistry.