Purity of Byzantine Gold

[Phillipe C]

How pure is Gold from the time of Justinian the first??

[cmcdon0923]

I believe they were essentially "pure" gold....at least as pure as their smelting technology allowed.  I recall reading somewhere that they were at least 22kt.

[Andrew McCabe]

The ancients could easily achieve 97- 98% in gold or silver when they wanted to, but getting over 99% seems to have proved difficult as analyses I've seen on Republican silver (theoretically pure) only rarely seems to reach 99%. The existence of trace elements soemetimes leads to an odd consequende that the value of residual gold in almost pure silver can at times reach 0.5% and thus at times can add substantially to a coin's theoretical value although not to their practical value as one wouldn't know what specific coins might have significant residual gold traces and as the seignorage would far exceed the typical (though not the exceptional) value of trace elements that might be recovered by a more thorough smelting and separation. 98% gold is 23.5 carats and I'd say that was typical of late Republican and early Imperial gold. I can't specifically comment on Byzantine but I'd assume it was similar.

[vercingetorix]

It's pure gold and they kept it unadulterated for many centuries. There are articles written about the gold content of Byzantine solidi.

[Posa]

According to "Cahiers Ernest Babelon  2 - Lór monnayé I" ( C.Morrisson et al.) the gold content is about 98,x %

Best regards

Posa

[Obryzum]

Do a google search for the article:

Andrew Oddy and Susan La Niece, Byzantine Gold Coins and Jewellery: A study of Gold Contents, Gold Bulletin (1986).  Here is a chart from the article showing the rapid debasement that began in the 11th century.  From the 4th Century to the 11th Century the fineness of the gold from the mint in Constantinople was stable.