Iron-rich variant of Glaucophane, which has iron dominating over the magnesium in a solid solutionseries. Ferro-Glaucophane is recognized by the IMA as a distinct mineral species with the following chemical formula: Na2Mg3Al2Si8O22(OH)2. There can be iron replacing some of the magnesium up to 50 percent.
See the full Glaucophane page for properties, photos, and additional varieties.
