Zimbabweite
Zimbabweite is a mineral; formula (Na,K)2PbAs4(Nb,Ta,Ti)4O18. It is generally classed as an arsenite but is notable for also containing niobium and tantalum. A yellow brown mineral with orthorhombic crystal habit and a hardness of 5. It was discovered in 1986 in kaolinized pegmatite, i.e. weathered to clay, in Zimbabwe.