The presence of the zeolite mineral yugawaralite (CaAl2Si6O16 4H2O) is reported in the Jurassic basaltic rocks of the Letaba Formation (Karoo Sequence) near Mkuze. Although many other members of the zeolite group have been reported from various localities in southern Africa, this is the first record of yugawaralite. Theyugawaralite occurs in association with laumontite, wairakite, calcite, and quartz in an exposure of the basaltic rocks on the banks of the Mkuze River at 27°35.50S 32°00.30E, 5 km northwest of the town of Mkuze, northern KwaZulu—Natal. The presence ofyugawaralite indicates that the basaltic rocks at Mkuze underwent a grade of alteration during the accumulation and post-eruptive development of the sequence differentfrom that elsewhere in the region, as it does not fit into the previously published zones of regional diagenesis and metamorphism. It is suggested that the formation ofyugawaralite at this site is related to a local dolerite dyke intruded at avery shallow depth.

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