stripes
Carter et al. (1963) report the occurrence of lavas about 3 km west of Lamja that are within Cretaceous Numanha shales. They are spheroidally weathered and in thin section reveal altered phenocrysts of olivine, abundant calcite and analcime with a groundmass of iddingsite, cloudy plagioclase laths and magnetite. Nepheline is reported as sometimes being present with a few samples containing leucite. Wright (1976) is suspicious about the accuracy of the identification of the last two minerals.
CARTER, J.D., BARBER, W. and TAIT, E.A. 1963. The geology of parts of Adamawa, Bauchi and Bornu Provinces in north-eastern Nigeria. Bulletin, Geological Survey of Nigeria, 30: 1-99.WRIGHT, J.B. 1976. Volcanic rocks in Nigeria. In C.A. Kogbe (ed) Geology of Nigeria, 93-142. Elizabethan Publishing, Lagos.