#28
Pma2
Example – Krennerite, (Au1-xAgx)Te2, x = 0 – 0.2
Krennerite was discovered in 1878 in Sacaramb, Romania, and first described by the Hungarian mineralogist Joseph Krenner (1839–1920).
http://webmineral.com/data/Krennerite.shtml
CIF
http://rruff.geo.arizona.edu/AMS/download.php?id=00124.cif&down=cif
The Fascination of Crystals and Symmetry 