Using a brief immersion in sodium thiosulphate, followed by aprox. 15 minutes of local application of (very concentrated) synthetic citric acid, followed gentle rubbing of a cotton swab and bamboo tooth stick on the iron oxides (reverse), I ended up with this: Gottfried II von Heinsberg, 1303-1331. Denar (Köpfchen), Blankenburg or Heinsberg mint. A local imitation of the contemporary coinage of the Dutch counts Floris V and Willem III. Rare - but this variant is even scarcer as the typical four flowers in the reverse fields are omitted. I restored this coin after a very busy ER shift of 12+ hours ... this gave me an immense satisfaction following the chaotic shift.