Alkaline Rocks and Carbonatites of the World

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Occurrence number: 
Chilwa Province
Longitude: 35.52, Latitude: -15.4

Mpyupyu is a small conical hill rising from recent sediments fringing the southwestern shores of Lake Chilwa. It consists of hornblende-biotite syenites, some of which contain a little quartz. There are rare pyroxene cores to the amphibole which is in turn mantled by biotite. Associated minor intrusions are microsyenite. Garson (1960) considered that a solvsbergite dyke outcropping near the foot of the hill is a ring dyke. Immediately south of the hill are several arcuate outcrops of pyrochlore-bearing aegirine-riebeckite syenite containing up to 1% pyrochlore, which is radio-active; Garson (1960) gives an analysis of the riebeckite.

BLOOMFIELD, K. 1965a. The geology of the Zomba area. Bulletin, Geological Survey of Malawi, 16: 1-193.GARSON, M.S. 1960. The geology of the Lake Chilwa area. Bulletin, Geological Survey of Nyasaland, 12: 1-67.
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