Emplaced in Precambrian (Ubendian) gneisses, the Mbozi complex has an overall length of 37 km and maximum width of 12 km.
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The four hills of Nakalulu, West and East Nachendezwaya and Nangwale are aligned northwest-southeast close to the border with Malawi and 3 km northeast of the Ilomba complex (Malawi No. 103-00-001).
Little information is available on the Makonde carbonatite. A rock described as 'apatite limestone' by Haldemann and Harpum (1952) forms a conformable layer 7 m thick by 140 m long within gneiss.
The volcanic rocks of the Fort Portal area extend over 142 km2 but have a volume of only 0.25 km3 (Nixon and Hornung, 1973). Kasekere is a contemporaneous field lying some 20 km to the northeast of the main Fort Portal field but extending over only 2.5 km2.
The Ndale volcanic field extends over an area of about 10x20 km (Geological Survey of Uganda 1:250,000 map 'Fort Portal'). The area is defined on the map as consisting of 'Volcanics: mainly tuffs with minor lavas': between 20 and 30 craters are indicated.
Mohokya comprises a line of six craters extending over 20 km in a north-northeasterly direction from the northern end of the Katwe-Kikorongo volcanic field (No. 5).
A 120 m diameter, circular body of limestone within Precambrian Toro schists was considered by Lytham (1979) to be carbonatite. However, rock analyses indicated that most trace elements, and notably the generally diagnostic ones, were below detection limits.
In the vicinity of N’tondongwe Hill four irregular bodies of metamorphosed carbonate rocks associated with magnetite, and lying within Precambrian biotite gneisses, were reported as being possible carbonatites. These are being investigated by K. Walsh (pers.
Nanuta was thought to be a metamorphosed carbonatite that had been intruded into granulites (Barber, 1991). It consists of two layers, each several kilometres long, lying conformably within Proterozoic paragneisses (mainly metabasites), xenoliths of which it includes.
The Kapfrugwa occurrence comprises an irregular body of carbonate-rich rocks lying in the axial area of a tightly plunging antiform of paragneiss (Barber, 1991). Two exposures described by Barton et al.