can Basalt Monolith untap itself

[Muk]

can i tap Basalt Monolith and untap its ownself?

[Kenji]

Well, obviously its Basalt Monolith's own activated ability that untaps it. But I get what you're asking: "Can I use the mana produced by Basalt Monolith to untap the same Basalt Monolith?"

The answer, of course, is yes. Basalt Monolith's mana ability gives you 3 colorless mana. And behold, Basalt Monolith can untap itself for 3 mana.

Though, clearly that doesn't give you any extra mana, since you're gaining 3 and spending 3 each time. There are ways to make 'infinite' mana, however. Rings of Brighthearth is one easy example.

"But, you can't use Rings to copy mana abilities!"

Well, no. We're not interested in copying the Monolith's mana ability. What we're interested in is the "3: Untap Basalt Monolith". Each activation of this + Rings of Brighthearth copy gives you 6 mana, but only costs 5 mana to do (3 for the original untap, 2 for the Rings' copy). So, have at it!