From Pathfinder Core Rulebook, which isn't enabled.

Solid Fog

SPELL 4

Traditions arcane, primal

Cast

Range 120 feet

Area 20-foot burst

Duration 1 minute

You conjure a bank of fog so thick it impedes movement as well as sight. This functions as Mist, except that the area is also difficult terrain. You can Dismiss the spell.

Pathfinder Core RulebookOGL