Bementite is a manganese silicate hydroxide mineral. The composition is variable, and there is much solid solution among the octahedral cations, as shown by the analyses in Table 16 . The texture, as best it can be deduced from the available hand specimens, is that of a breccia wherein abundant bementite hosts large angular shards of sparser calcite. Barite is both present and extensively replaced in this assemblage, and growth patterns of the bementite commonly intersect at 90 o . Calcite is sparse.
Several specimens suggest bementite forms by alteration of pre-existing friedelite.
At least one specimen, which compares well in color, texture, and X-ray powder pattern with Franklin bementite, was found at Sterling Hill. Name Bementite was named for Clarence S. Bement, a Philadelphia mineral collector.