Dust motes dance in the afternoon sun. They swirl around the crumbling remains of the Coimadoi Antimony Mine Processing Plant. Imagine the bustling activity here decades ago.
The Coimadoi Antimony Mine Processing Plant near Bacchus Marsh wasn’t just a mine. It was a vital part of Australia’s industrial history. It operated intermittently from its discovery in 1887 until 1915. Then it saw renewed activity between 1942 and 1944. This plant played a crucial role in supplying antimony during wartime. Antimony was a key component in the manufacturing of munitions.
The orebodies themselves were located in Lower Ordovician slate and sandstone. These rocks were intensely sheared. The lodes formed in fault zones. Two main sections existed: Draper’s and Bondison’s. Draper’s lode system struck north-northwest and dipped steeply west. Bondison’s lode struck east-northeast dipping sharply north. In Draper’s section most ore above the adit level was extracted early on. However around 400 tons of 5% Sb ore were developed below. Prospects for more ore were deemed good in 1943.
Interestingly gold values were significantly higher in Bondison’s section than Draper’s. Few assay data however are available on the gold or antimony content. The plant processed the ore extracted from these two lodes. The specific processing methods aren’t documented in our readily available sources. However imagine the clatter of machinery. The rhythmic thud of crushing and separation. The smell of dust and ore.
Beyond the antimony itself minerals like galena and aurostibite were also found. Aurostibite is an antimony-gold alloy. Free gold was found in the upper levels of the mine. The gangue mineral a type of waste rock associated with the ore was predominantly quartz. After processing the refined antimony was transported elsewhere. It contributed to Australia’s war effort and beyond.
Today silence hangs heavy over the Coimadoi Antimony Mine Processing Plant. Only ghosts of industry remain. The crumbling structures stand as a testament to a bygone era. They whisper stories of miners and their work. They speak of a time when this quiet valley was alive with the rhythm of industry. They also showcase a significant chapter in Australia’s mining history. A chapter largely forgotten by most.