Tantal-Pegmatit. Geologische, petrologische und geochemische Untersuchungen. (Monograph Series on Mineral Deposits, No.23).

Ta-bearing granitic pegmatites and their dispersion aureoles have been investigated. Those studied in detail include the pegmatites of the Cat Lake-Winnipeg River area, Manitoba (Tanco and six others); the Harding pegmatite, New Mexico; Tip Top pegmatite, South Dakota; pegmatites of the Namaqua Province, southern Africa; and pegmatites of E Bavaria. Trace-element data are given for country rocks, xenoliths and pegmatites and for numerous pegmatitic minerals, and major-element XRF results are given for eight white micas (mainly from the Tanco pegmatite). The early white-mica generations are the most suitable for exploration, as their Ta content correlates with the grade of Ta mineralization. The observed correlation between Ta and rare alkalis (Rb,Cs) suggests that Ta accumulation in pegmatites is exclusively the result of magmatic fractionation. Most complex Ta-pegmatites are found, however, in amphibolites rather than in micaceous metasediments, and the relationship between the Ta-Cs-bearing pegmatites and their ortho-amphibolite country rocks may be significant.-R.A.H.