Kraus book is where I got it from. There was green, black and red. Green was for truppen from 3rd Jäger Rgt, Bavarian and Prussian Gebirgs MG, Württemberg Gebirgs truppen (Both Schützen and MG used the green, minus their Gebirgs Artillery). Black was for Gebirgs Artillery, so Bavarian, Prussian and Württ Gebirgs Artillery would use the black. Red was for Gebirgs Minenwerfer, so Bavarian and Prussian Gebirgs Minenwerfer would use red. Württemberg didn't have Gebirgs Minenwerfer. As for the caps them selves, Bavaria and Prussia's Bergmütze had a vulcanfiber visor painted feldgrau, while Württemberg's Bergmütze had wool visor. There were private purchased version for both. Both came with a full liner with leather sweat band, and air vents. The issued version had partial lining and a cloth sweatband.
#1 Green piping
#2 Red piping
#3 Black piping
#4 Green piping
#5 Black piping on both caps