GYPSUM
Introduction.
High-grade rock gypsum and impure earthly or
sandy gypsite are known in Tanzania. Rock gypsum in association with beds of
anhydrite and rock salty occur in the Mesozoic sedimentary sequence in the
Southeast Kilwa District. Gypsite is more widespread than the rock variety.
Four localities contain gypsite, namely, Mkomazi in Lushoto District,
Msagali in Mpwapwa District, Itigi in Manyoni District and Mtegu in Lindi
District.
Kilwa District.
Rock gypsum occurs in association with beds,
which make up part of the Mesozoic sedimentary sequence in the southeastern
Kilwa District. There are three localities of gypsum rock: Pindora, Mbaru
(Nondwa southern part of Mandawa) and Mkomore. Reserves of 2 million tonnes
of gypsum with an average grade of90% have been estimated.
Mkomazi.
The gypsum is of
three types: nodular, flake and powder. The grade of the gypsum varies from
70% to 85%. Total reserves are estimated at 829,000 tonnes
Makanya.
Five type of gypsum are present at Makanya,
namely rock gypsum, gypsite, alabaster, satin spar and selenite. Reserves of
over 1.0Mt grading 82% gypsum have been estimated. The Mkomazi and Makanya
gypsum deposits are mined at a small-scale level and the gypsum is being
used in the cement industry.
Itigi.
Gypsiferous clay
and gypsum bands have been formed in an area of internal drainage in which
shallow lades have been develop. Reserves estimated at 15,000tonnes with an
average grade of 70-75 percent gypsum. The deposit is mined by small-scale
miners.
Msagali.
The deposit is situated at Msagali in the
Mpwapwa District, Dodoma Region in Central Tanzania. The gypsum is soft and
porous (gypsite) and occurs in beds near the surface with a purity of up to
75%. The deposit is mined and used in the cement industry.