Chemical composition of todorokite

Abstract

New analyses were given for 4 todorokites from different localities in Japan. The chemical formulae of 4 specimens calculated on the basis O=7.00 are as follows:
Fukaura mine: (Mn²⁺_0.56, Ca_0.20, Ba_0.04, Mg_0.10, Na_0.12, K_0.08) _1.10 Mn⁴⁺_3.00 O_7.00•2.1H₂O
Maruyama mine: (Mn²⁺_0.57, Ca_0.09, Ba_0.03, Mg_0.20, Na_0.12, K_0.06)_1.07 Mn⁴⁺_3.02 O_7.00•2.1H₂O
Hongômine: (Mn²⁺_0.53, Ca_0.05, Ba_0.01, Mg_0.08, Na_0.05, K_0.03)_0.75 Mn⁴⁺_3.13 O_7.00•2.3H₂O
Hamayokokawa mine: (Mn²⁺_0.58, Ca_0.22, Ba_0.06, Mg_0.05, Na_0.01, K_0.05)_0.07 Mn⁴⁺_3.03 O_7.00 • 1.8H₂0
Therefore, it is proposed that a logical formula for todorokite is: (Mn²⁺, Ca, Ba, Mg, Na, K)Mn⁴⁺₃ O₇•2±xH₂O