Alluvial gold was discovered in September 1851 in the Araluen Valley. Almost overnight, thousands of prospectors moved to the area.

Within a year an estimated 100,000 ozs of gold had been recovered, earning the area a reputation of being one of the richest goldfields in Australia...

Roads, railways and tramways in New South Wales - all being extended over long distances in the second half of the 18th century - required blue metal. Enormous quantities of it.

Basalt in the Bombo-Kiama area was abundant, could easily be quarried and crushed into blue metal, and could then be shipped with relative ease to major centres such as Sydney. So, from the 1880s, Bombo-Kiama became the primary source of supply of blue metal in NSW...