Polonium is the rarest isotope you will mine. It will start to occur at level 55 and achieve maximum at 84 (upgrades and miners still increase the amount you get, but not depth).
Polonium is available as three different isotopes.
 Polonium 1
|
$5,000 / unit |
 Polonium 2
|
$250,000 / unit |
 Polonium 3
|
$50,000,000 / unit |
It is a requirement for the following upgrades (v0.14/19 mar 2021):
| Recipe | Polonium 1
|
Polonium 2
|
Polonium 3
|
|---|---|---|---|
| Giant_Cargo | 500 | ||
| Fission Engine | 500 | ||
| Enormous Cargo | 500 | ||
| Drill King Engine | 1,000 | ||
| Drill Lord Engine | 3,000 | 75 | |
| Demon Smasher Drill | 100 | ||
| Gold King Cargo | 10,000 | ||
| Seismic Resonance Engine | 75 | ||
| Gravity Engine | 100 | ||
| Core Reactor Engine | 125 | ||
| Purple Forged Gem | 25 |