AM_Talc Formula: Mg3 Si4 O12 H2 Name: Talc Unit cell: 5.26 9.1 18.81 90.0 100.0 90.0 , V=886.68 Space group: C12/C1 (15)

Gruner J W , Zeitschrift fur Kristallographie , 88 (1934) p.412-419, The crystal structures of talc and pyrophyllite, Locality: Harford County, Maryland, USA