Tags: Chemical Substance, Mineral.
Todorokite is a rare complex hydrous manganese oxide mineral with the formula (NaCaKBaSr)1-x(MnMgAl)6O12·3-4H2O. It was named in 1934 for the type locality the Todoroki mine Hokkaido Japan. It belongs to the prismatic class 2/m of the monoclinic crystal system but the angle β between the a and c axes is close to 90° making it seem orthorhombic. It is a brown to black mineral which occurs in massive or tuberose forms.
