One of the more interesting aspects of Australia pre-decimal history is the nature of gold’s conversion into colonial currency. Whereas the UK minted currency is 22k with remaining copper, natural gold tends to alloy with various metals.

Furthermore, did you know that gold is believed to be created in the destruction of stars; when they collapse and go supernova? (fig. 0) I didn’t either, until about two years ago. So when I wax lyrical over the gold Darius in my collection, I am reminded that this 2400yr old culturally important artefact is actually one of the more ancient materials of this universe.  

Image of a Nebula Galaxy

credit: Wikipedia

Which gives me to thinking of the following question. How did the earliest civilizations have the processes to create 98% gold purity when Alexander the Great was conquering the known and unknown world, yet mint officials in the NSW Colony couldn’t manage the separation of gold alloy until the late 1860’s? These are the sort of thoughts that plague my mind, yet give rise to articles that hopefully interest CAB readers.

Geoffrey Heidemann of Cockatoo Coins (and moonlighting gold geologist) reports the following mines as supplying Sydney Mint – Sofala & Bathurst – while Beechworth, Ballarat and Bendigo fed the Melbourne Mint. Barring a more detailed analysis of gold shipments that illustrates otherwise, the following gold alloys were likely mined in NSW. The alloys are composed of gold (Au), silver (Ag) and copper (Cu), with trace Iron (Fe).

 

Fig. 1 Fig. 2 Fig. 3

Au 91.78

Au 91.38

Au 91.84

Ag 5.52

Ag 5.81

Cu 4.73

Cu 2.70

Cu 2.52

Ag 3.43

+ trace Fe

 

 

 

 

 

FIG. 1 – 3

Figure 3 is the interesting mix. I had purchased this coin specifically to record the introduction of gold separation techniques that permitted the Sydney and Melbourne’s Mints to create Imperial quality gold coins shortly afterwards. Dr David Briggs reports that it wasn’t minted in 1866, but two to three years later. The alloy is not what I had anticipated. While the colour suggested plenty of copper, there’s a surprising amount of silver. Briggs’s “Half Sovereigns” 2nd ed. mentions that the mint was experimenting to get the technique down pat. More research required. See https://www.lbma.org.uk/wonders-of-gold/items/miller-process for more information.

Unfortunately the only comparative analysis one can make of Victorian natural gold alloy in Australian pre-decimal is in the 1852 Adelaide Pounds. The example in my collection is locked up in a PCGS slab. Geoff indicated that fire assay would be necessary to determine trace elements and subsequently make an attempt at researching the mine origins. There are some banged up half sovereigns out there and such a destructive outcome may be considered before gold hits $3000 AUD oz and makes this idea ridiculously expensive.

These quick articles in CAB will be progressively fleshed out into larger research projects and eventually – in the case of half sovereigns – a modern guidebook meeting the needs of informed collectors. If you have information or feedback you’d like to see freely credited to yourself in future articles – topendcoins@gmail.com. Cheers, Les 0455 660 884.