Wikipedia
Cleusonite
Cleusonite is a member of the crichtonite group of minerals with a chemical formula of (Pb,Sr)(U,U)(Fe,Zn)(Ti,Fe,Fe)(O,OH). This group of minerals contains approximately thirteen complex metal titanates. The structures of minerals of this group is complicated by frequent fine-scale twinning and metamictization due to radioactive elements. The crichtonite group consists of members of related mineral species of the type A{BCDE}O which are characterized by their predominant cations (as seen in crichtonite (Sr), senaite (Pb), davidite (REE + U), landauite (Na), loveringite (Ca), lindsleyite (Ba), and mathiasite (K).