THE GEOLOGY, MINERALOGY AND GEOCHEMISTRY OF
GEMSTONES IN TAITA TAVETA MOZAMBIQUE BELT SEGMENT, IN
RELATION TO GONDWANALAND
ABSTRACT
The Mozambique Belt averages 250 and 325 kilometers (150 and 200 miles) in
width and extends up the east coast of Africa from Mozambique northward at least
5,000 kilometers (3,000 miles) through East Africa.
It consists of high grade metamorphic rocks of higher amphibolite to granulite
facies. The area is of high grade metamorphosed rocks and south of the area
gneissic hills is abundant with garnets. North Eastern slopes of Reata are feldspar
porphyroblasts and hornblende- hypersthene- diopside assemblages on Mokinni
and Latema and hornblende- diopside- garnet- biotie assemblages on Munyoni and
Vilima Viwili. Near the Eastern boundary pure quartzite overling quartz kayanite
schist with leticular kyanite segregations in Murka Loosile belt.
The Rombo series occupy ground between Tsavo and the Northern boundery of the
area with dense basalts, Kijabe type basalts with olivine soda trachytes and
melocratic basalts with olivine,augite, porphyritic picrite basalts. Lavas and ashes
of subsidiary cones such as Worombo and Lamrrica consists of vesicular olivine
basalts, slopes of ash scoriaceous and olivine basalts contaminated by lapilli and
ash. Between Lumi and Marve rivers float blocks of crananite, a variety of olivineanalcite dolerite containing orthoclase by Bear, 1955 investigation.
The geology of Sri Lanka is similar, mainly composed of highgrade metamorphic
rocks in a Precambrian terrain. These rocks form three major lithotectonic units
namely, the Highland Complex, the Vijayan Complex, and the Wanni Complex.
Among these, the Highland Complex is the largest unit and forms the backbone of
the Precambrian rocks of Sri Lanka. Included in this unit are the super crustal rocks
of the former Highland Series (Group) and the South western Group together with
a variety of igneous intrusions of predominantly granitoid composition that now
occur as banded gneisses. The geochemistry and mineralogy of the rocks in Taita
Taveta is also similar to those in the Gondwanaland due to the similarity in their
geologies. Common gemstones are dominantly observed in the Mozambique belt
in correlation to Pan African belt of Sri Lanka, Tanzania, Mozambique and
Southern India.