What about the Crystal Cone

Hint 1 of 5:

It is needed for assault on the Crystal Planet.

Hint 2 of 5:

It will indentify the proper location to arm the Black Egg.

Hint 3 of 5:

If you're not pressed for time, go mining on the Crystal Planet.

Hint 4 of 5:

The whole planet is going to blow anyway, after your attack.