You had a chance of digging these up during Tibia's 20th Anniversary inside Vigintia's treasure hunting zone.
You can see some golden nuggets in a locked room under Venore Bank, also in Omruc's pharaoh room below Ankrahmun, and locked in chambers in the Circle Room Quest. Probably also a few other places around Tibia.
These existed in-game long before they were made obtainable during Tibia's 20th Anniversary. Rumour has it that someone with Key 0000 in his possession managed to steal them from the room in Venore back in the day, but that CipSoft knew about this and deactivated the key after taking the nuggets back.