1) Monoclinic mineral 
Kaersutite is a dark brown to black double chain calcic titanium bearing amphibole mineral with formula: NaCa2(Mg3Ti4+Al)(Si6Al2)O22O2. Ferro-kaersutite is the divalent iron rich endmember of the kaersutite group, with the iron replacing magnesium in the structure. It occurs as phenocrysts in alkalic volcanic rocks; in nodules of peridotite and ga...