Heavy metals are here treated as light metals and, in general, are not further considered. The heaviness of naturally occurring metals such as gold, copper, and iron may have been noticed in prehistory and, in light of their malleability, led to the first attempts to craft metal ornaments, tools, and weapons. All metals discovered from then until 1809 had relatively high densities; their heaviness was regarded as a singularly distinguishing criterion. From 1809 onwards, light metals such as sodium, potassium, and strontium were isolated. Their low densities challenged conventional wisdom and it was proposed to refer to them as "metalloids" (meaning "resembling
Federated Moulders' (Metals) Union of Australia the Amalgamated Metals, Foundry and Shipwrights' Union in February 1983. Federated Moulders' (Metals) Union of Australia The Federated Moulders' (Metals) Union of Australia (FMMUA) was an Australian trade union which existed between 1899 and 1983. It represented moulders - skilled tradesmen who fabricated the moulds used to cast metal products in foundries. Despite its exclusive attitude towards membership, which kept the total number of FMMUA members low throughout its existence, the vital position of moulders in major industries such as mining, manufacturing and the railways ensured that the union remained industrially powerful, and the union had a reputation for being