This arrangement of mineral species is based on Dana's New Mineralogy by Richard V. Gaines, H. Catherine Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig, with sections by Vandall T. King, Illustrations by Eric Dowty, (ISBN: 047119310-0) Copyright © 1997, John Wiley & Sons, Inc.". This material is used by permission of John Wiley & Sons, Inc. Follow this link for a short discussion on the Dana Classification Number.
71.02.01 Pyrophyllite-talc group 71.02.01.01 Pyrophyllite Al2Si4O10(OH)2 P1 1 71.02.01.02 Ferripyrophyllite Fe+++2Si4O10(OH)2 C 2/m 2/m 71.02.01.03 Talc Mg3Si4O10(OH)2 C 2/c 2/m 71.02.01.04 Willemseite (Ni,Mg)3Si4O10(OH)2 C 2/c 2/m 71.02.01.05 Minnesotaite (Fe++,Mg)3Si4O10(OH)2 C1 1 71.02.01.06 Brinrobertsite! (Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4•3.54(H2O) [x = 0.35, n = 3.54] pseudo 2/m 2/m