Music ornamentation?

Question

I've been playing the piano for years but recently I stumbled across a notation I've never seen before. It looks like three bold parallel slanted lines between two whole notes. Other times there are two lines, and when it is used to connect half notes the two lines make them look like two 16th notes with white heads lol Anyone tell me what this means?

Answer 1

Yes! This is a method of subdivision notation, or tremolo:
http://en.wikipedia.org/wiki/Tremolo

The three parallel lines means to rapidly play the notes designated for a quarter note's time.

The two lines between two half notes mean to do the same thing, but for one half notes' time.
Sometimes the use of just two lines on the stem of the note can mean to do tremolo in time with the rhythm of the piece (i.e. play 16th notes or 32d notes rather than just rolling as fast as you can). You see this notation all the time in string music. Usually, though, in piano music, it's just a rapid "roll" between the two notes.

Answer 2

The three lines between two whole notes mean to alternate those pitches in 32nd notes, for the length of a whole note. The two lines between two half notes meant to alternate in 16th notes, for the length of a half note.