Geology And Mineral Potential of Taita Taveta County
The original Taita Taveta County has been divided into four districts namely Taita, Taveta, Mwatate and Voi. The geology of the area can be divided into three regions:
1.    Taita hills
2.    Taveta area
3.    Mwatate area.

i.    Taita Hills
The rocks here can be divided into two types;
(a) Mozambique Belt (Basement System)
•   Rocks here include;
•   Quartz Feldspar gneiss
•    Quartzites
•    Graphite Gneiss Banded Biotite Gneiss
•    Kyanite Sillimanite (-Garnet-Biotite) Gneisses
•    Marble
•    Calc-silicate rocks
•    Amphibolites
•    Ultra Mafic rocks
•    Migmatites
•    Pegmatites
(b) Superficial Deposits
Three types evident;
•    Alluvium- Gravels, silts and sands, mainly along rivers
•    Colluvium-Frequently heavily gullied, slopes gently into surrounding pediplain.
•    Soils-Kaolinitic or light coloured sandy soils, Residual ferralitic reddish sandy soils.

ii. Taveta Area
The rocks are divided into three groups;
(a)    Mozambique Belt (Basement system) - Is poorly exposed, outcrops confined to the inselbergs and few dry river valleys and gullies.
(b)    Tertiary volcanic - Consists of lava flows, some of which have erupted from Mt. Kilimanjaro, others from subsidiary vents on the plains. May be divided into;
 Rombo series which the following succession:
•    Kijabe type Basalts and olivine soda trachytes
•    Melanocratic basalts with olivine and augite phenocrysts
•    Dense basalts
          Lavas and ashes of subsidiary cones - lavas extruded from volcanoes on
          The plains and consists of essentially vesicular olivine basalts.
(c)    Pleistocene and Recent Deposits
Includes calcareous tuffaceous grits, lacustrine deposits at Lake Jipe, alluvium along the Tsavo River and Secondary Limestone around Salaita and between Salaita and Vilima Viwili.

iii.    Mwatate Quadrangle
This area lies entirely within the Mozambique Belt. It’s completely within the domain of the suite of meta-pelites and meta-calcareous rocks named Kurase series by SAGGERSON (1962). The Kurase series is further subdivided into the following formations;
(1)    The Mugeno Formation.
(2)    The Mwatate Formation.
(3)    The Mgama Mindi Formation.
(4)    The Mtonga-Kore Charnockite Complex.
(5)    The Lualenyi member.
(6)    The Mtongore Formation.


Taita Taveta is endowed with a number of gemstones and industrial minerals.
The gemstones that are mined here include;
1.    Garnets (Tsavorite, Rhodolite, red garnet, yellow garnet, Change colour etc.)
2.    Corundum (Ruby and Sapphire)
3.    Amethyst
4.    Tourmaline (yellow, green, black etc.)
5.    Peridot
6.    Iolite
7.    Spinel
Industrial minerals that occur here include;
1.    Iron ore
2.    Limestone
3.    Copper
4.    Manganese
5.    Marble
6.    Magnesite
7.    Asbestos
8.    Graphite
9.    Kaolin Clay
10.    Mica
11.    Building stones

i.    Ruby and Sapphire (corundum)
These are found in aluminous gneisses and granulites and are often associated with silimanite, kyanite and almandine garnets. Rubies normally occur in prismatic or tabular form while sapphire occurs as truncated dipyramidal crystals of blue or purple colour.

They occur in:
  •     Desilicated plumasitic pegmatite cutting across ultramafic rocks
  •     Desilicated zones at the contact of ultramafic rocks with paragneisses
  •     In metamorphosed aluminous sediments
  •     In marble
  •     As placer deposits

Only the first two occurrences are of economic importance, the rest being hosts to small scattered grains. Secondary enrichment of corundum during weathering may lead to the formation of occasionally rich aluvial placer deposits. These have not yet been discovered. Examples are at Mangari (associated with an ultramafic body and pegmatites), at Kishushe (pink corundum) in pegmatite with accessory black tourmaline. It is also found at the contact of ultramafic rocks with felsic gneisses where silica rims have developed consisting of vermiculate pockets in which pinkish corundum is embedded.

ii.    Tsavorite
This is the green grossularite garnet and occurs in a suite of silimanite-bearing graphite gneisses in the upper part of Lualenyi member in the Mgama-Mindi area. It occurs as scattered porphyroblasts 5-19cm with kelyphitic rims. It is associated with vanadium calc-silicate such as zoisite (tanzanite), sphene and diopside. An association of graphite gneisses and marble is mandatory for the formation of green garnets. Local stretching lineations appear as good guide to pockets.

iii.    Tourmaline
These are associated either with ultramafic rocks or with metalimestones. The colour is related to the presence of Ti, V and/or Cr. They also occur in pegmatites, in fault zones, and in the ultramafic rocks. At Kisoli hill, Magnesium tourmaline occurs in mica rich vein let cutting across marble.

Industrial Minerals

Apart from the gemstones, the Taita area also hosts a number of industrial minerals. These include Magnesite, Asbestos, Graphite, Kaolin Clay, Mica, Magnetite and Building stones.

Magnesite (MgCO3) occurs in numerous sites and is associated with dunites-serpentinite complexes. It is generally highly siliceous and not suited for high quality refractories but is suitable for agricultural application. Anthophylite asbestos occurs in a serpentine complex at Mwakinyambu, associated with some talc and vermiculite. However, the fibres are short and therefore not suitable for industrial application.
Numerous graphite gneisses occur in the area e.g. the Chawia, Mwatate and Tsavo prospects.

Kaolin is solely of supergene origin and is therefore restricted to the Taita hills e.g. Mghambonyi area. The resource potential is quite substantial.

Muscovite “books” occur frequently in zoned tourmaline pegmatites e.g. at Mgange. The reserves are not known.

Marble is quarried locally at small scale. Due to high MgO content, it is only suitable for burning to make lime and as dimension stone or aggregate.

Magnetite (Iron ore) occurs in most parts of the County but mining is ongoing at Kishushe area.
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