My periodic table poster is now available! Gehlenite. Description from the source: Gehlenite ( Ca2 Al (Al Si) O7 tet.), Le Selle, Monzoni, Trento, Italy. Small but evident. 1,5x1x1 cm; 3 g with box. Source: Simone Citon Contributor: John Gray Acquired: 14 October, 2008 Text Updated: 14 October, 2008 Price: Trade Size: 0.6" Composition: Ca2Al(AlSi)O7