Gold is not just the most valuable resource in Prospectors, but also an in-game currency. The Prospectors world is functioning due to the laws of free economics, i.e., the prices are formed according to the supply & demand ratio. All the inner game relations require the use of gold. Players buy and sell goods for gold, pay salaries to the hired workers, handle rent and taxes. The same gold is mined in the gold mines. The external representation of gold is PGL. You can always put additional funds in the game by converting PGL into gold or vise versa. For that, find the menu “Account Settings” in the right top corner of the window.
The exchange rate is 1PGL = 1000 gold.
In the tab "Exchange", you can put PGL in the game by converting it into game gold and vice versa.