ferro-glaucophane
Iron-rich variant of Glaucophane, which has iron dominating over the magnesium in a
solid solution series. Ferro-Glaucophane is recognized by the
IMA as a distinct mineral species with the following chemical formula: Na
2Mg
3Al
2Si
8O
22(OH)
2. There can be iron replacing some of the magnesium up to 50 percent.