Why does gold explode purple?

[Paul Ferguson]

"Fulminating gold – the name comes from the older meaning of “fulminate”, viz, “explode” – was the first high explosive ever discovered. The earliest reference to its creation comes from 1585, in a book by the German alchemist Sebald Schwaerzer, and it’s been popular ever since with just about everybody – from academic chemists to popular YouTubers."

https://www.iflscience.com/400-year-old-...dJT29kPkxw