Strange "x" in front of notehead

Question

I was reading some piano sheet music and came across a type of note that looked like a sharp. Here is how it looked:

What is this type of note called? What is its pitch?

Answer 1

Probably already answered elsewhere. But see if this explanation helps.

It's a Double-sharp. Raises the pitch by 2 semitones (a normal sharp raises it by one).

You're most likely to find it as the sharpened 7th note of a minor scale in a key with lots of sharps! For instance, Fx is the seventh note of G# (harmonic) minor. Not an impossibly remote key, a piece in B major might well pay it a visit.

Why not just write G natural? Well, a scale needs to LOOK like a scale, with one of each note, And a triad needs to LOOK like a triad, visibly spaced in thirds.

(You can have double-flats too. We just use two flat symbols for that.)

(And I can't tell you the pitch of your example, because there's no clef.)