Zimbabweite

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