...and you have no idea what color it is so you can replace it?
I sent the image of the broken stick to Dakota Art Pastels to see if they could identify it for me. They made their best guess: Sennelier 478 Purplish Blue Gray. Thank you Dakota!
During my search in the studio for a clue about what this pastel was, I opened my Schmincke box and found the color charts I made when I purchased the set. Also in the Schmincke box I found I had stored duplicates regardless of brand. That is why, when you look a the photo below, it appears labeled colors are broken in half and both halves are in the box. Each papered stick is a separate color. Next time, maybe I'll drop a Schmincke and replacing it will be easier.