stripes
Occurrence number:
049-00-035
Country:
Egypt
Location:
Longitude: 33.3, Latitude: 23.3
Carbonatite:
No
The exposed part of the Um Risha complex measures 12 km east-west but an unknown area is concealed beneath Nubian sandstone. The intrusive rocks are peralkaline syenites and granites of varying grain size. The principal mafic minerals are aegirine-augite and a range of amphiboles including riebeckitic types. What are taken to be remnants of a volcanic cone include pyroclastic rocks, trachyte and trachybasalt, the trachyte containing aegirine-augite, amphibole and sanidine. There are a few bostonite dykes within the complex.
References:
EL RAMLY, M.F., ARMANIOUS, L.K. and HUSSEIN, A.A.A. 1979. The two ring complexes of Hadayib and Umm Risha, SE. Desert. Annals of the Geological Survey of Egypt, 9: 61-9.
Location: