We present electron-microprobe and single-crystal X-ray-diffraction data for a microlite-group mineral with a formula near NaCaTa2O6F from the Morro Redondo mine, Coronel Murta, Minas Gerais, Brazil. On the basis of these data, the formula is A(Na0.88Ca0.88Pb0.02□0.22)Σ2.00B(Ta1.70Nb0.14Si0.12As0.04)Σ2.00X[(O5.75(OH)0.25]Σ6.00Y(F0.73□0.27)Σ1.00. According to the new nomenclature for the pyrochlore-supergroup minerals, it is intermediate between fluornatromicrolite and “fluorcalciomicrolite”. The crystal structure, Fd3̅m, a = 10.4396(12) Å, has been refined to an R1 value of 0.0258 (wR2 = 0.0715) for 107 reflections (MoKα radiation). There is a scarcity of crystal-chemical data for pyrochlore-supergroup minerals in the literature. A compilation of these data is presented here.