Rhodonite crystals, a selection of specimens of this crystallized mineral species. Rhodonite is a mineral with many collector’s items presented here with a description, one or more photos and sometimes a video. These rhodonites are for sale. It is a manganese silicate, with iron, magnesium or calcium, with the chemical formula (Mn2+,Fe2+,Mg,Ca)SiO3, triclinic crystal system.