Diatomite in Ethiopia

Diatomite in Ethiopia
MINERAL RESOURCES OF
The most favourable site for accumulation
of fresh-water diatomite
deposits in Ethiopia is the Main
Ethiopian Rift valley with its widespread
silicic volcanism and lacustrine
basins.
The suitable environment for the formation
of diatomite is present in the form of:
• Rift volcanism with sediment supply
• Ground-water chemical composition
and hydrothermal activity
• Caldera collapse
• Formation of lacustrine basins
• Lake water with high levels of dissolved
silica and abundant nutrients
• Rapid growth and accumulation of
diatomaceous oozes forming diatomite
Adami Tulu
Gada Motta
Abiyata
Lake
Tana
High-grade Precambrian
Undifferentiated gneisses
and schists
Low-grade Precambrian
Metavolcano-sediments
Metaultramafic-mafics
Addis Ababa
Main Ethipoian Rift
Precambrian
Phanerozoic Intrusives
Gabbro
Diorite
Granite-tonalite
Palaeozoic Rocks
Tillites
Hade Hulu
Chefe Jila
Mesozoic Rocks
Undifferentiated sediments
Geology: Modified from Mengesha et al.(1996)
Geological map of Ethiopia, second edition, 1:2,000,000
Cenozoic Rocks
Early-Mid Tertiary basalt
Upper Tertiary-Quaternary - basalt
Mid Tertiary-Quaternary - felsic rocks
Early Tertiary sediment
Upper Tertiary-Quaternary sediment
The geology of Ethiopia can be divided
into three major groups: The Pre cam -
brian basement (1), the late Tertiary–
Mesozoic sedimentary successions (2)
and Tertiary–Quaternary volcanics and
sediments (3). The volcanics are associated
with the evolution of the East African
Rift System.
The volcanic rocks cover about 40% of
Ethiopia and Palaeogene plateau basalts
Diatomite deposit at Adami-Tulu area.
Simplified geological map of Ethiopia with diatomite deposits in Eastern and Western Ethiopia.
cover 25% of these. The Quaternary sediments
occur throughout the country and
were created as lacustrine as well as
marine formations. They include limestones,
clay, siltstone, sand, volcaniclastics,
and cover about 11% of the total
area of Ethiopia. The Cenozoic sediments
and volcanic rocks are important industrial
mineral resources including construction
materials, potash, rock salt,
gypsum, bentonite, diatomite, pumice,
sulphur etc.
The best diatomite deposits are found
in the central part of the rift and include
the Gade Motta, Adamitulu, Chefe Jilla
and Abiyata deposits. All known deposits
are lacustrine of origin and Tertiary–
Quaternary of age are found in or near
major volcanic structures.
The Gada Motta caldera is a semi-circular,
volcano-tectonic structure about 15 km
in diameter. The rim of the caldera rises up
to 400 m above the surrounding plain. It is
mainly composed of rhyolite and consolidated,
water-lain, tuffaceous siltstones of
lower Pleistocene age. The entire sequence
is overlain by brecciated pumice and
pumiceous ash and glassy ignimbrite.
The high-grade ores of Chefe Jilla,
Adami Tulu and Gada Motta have SiO 2
ranging from 84.5 to 86.5%, Al 2 O 3 from
3.1 to 3.7%, Fe 2 O 3 from 1.5 to 2.4% and
CaO from 0.1 to 1.9%. Slightly higher values
of alumina, iron and calcium can be

Ministry of Mines of Ethiopia
Dear Investors,
MINERAL RESOURCES OF
Diatomite deposit at Chefe-Jila area.
ascribed to the association of volcanic ash,
clay and calcareous concretions.
According to their physico-chemical char-
The chemical composition, location and
resource and physical tests are shown in
tables 1 to 3.
We take this opportunity to welcome you
to Ethiopia.
We promise to make every possible effort
to provide you with all required information
on the mineral sector in Ethiopia.
If you require information on the mining
law, licensing conditions and the investment
climate in Ethiopia, please contact
the Mineral Licensing and Administration
Department:
Ministry of Mines
Mineral Licensing and Administration
acteristics, the high quality diatomite can be
Department
used for filtration and as a catalyst carrier in
the chemical industry. Diatomite of lower
Opportunities
P.O. Box 486
Addis Ababa, Ethiopia
quality can also be used as pesticide carrier,
filler, thermal insulating material and lightweight
bricks. The total resources of Gade
The main Ethiopian Rift, due to its widespread
silica volcanism and lacustrine basins, is the
most favorable site for the accumulation of
Tel. +251 11 6461214
Fax +251 11 6463454
Motta, Adami Tulu, Chefe Jilla and Abiyata
diatomite are more than 40 million tons of
fresh water diatomite deposits. Occurrences of
Diatomite are also encountered in Anani,
Email: information@mome.gov.et
www.mome.gov.et
which about 85% are contributed by the
Wonji, Arba, Kora, Afdem, Bishan Karabe and
Gade Motta diatomite.
by the Derba river and the Lefleta stream.
Table 1 Chemical Compositions of diatomite (%)
Locality Oxide (weight %)
SiO 2
Al 2
O 3
Fe 2
O 3
CaO MgO Na 2
O K 2
O MnO TiO 2
P 2
O 5
H 2
O LOI
Chefe Jilla 84.5 3.14 1.5 1.89 0.72 1.64 0.78 0.02 0.2 0.34 - 4.68
Adami Tulu 86.7 3.36 2.2 0.14 0.22 1.63 0.84 0.03 0.2 0.62 - 3.66
Gada Mota 85.5 3.68 2.4 1.11 0.36 1.18 0.73 0.04 0.28 0.38 - 3.78
Table 2 Location and resource of diatomite of Ethiopia
Area Name of Resource Easting Northing Resource
(province) deposits group* (million tons)
Lakes Region Abiyata (1, 2) 38°28´00´´E 07°40´00´´N 5.05
Lakes Region Adami Tulu 2 38°45´30´´E 07°51´00´´N 0.2
Lakes Region Chefe Jilla 2 38°51´20´´E 07°50´30´´N 0.055
Lakes Region Gada Motta (1, 2, 3) 38°38´45´´E 07°51´22´´N 35.6
W. Hararghe Hade Hulu 2 40°18´48´´E 08°54´14´´N 4.2
* 1 - measured, 2 - indicated, 3 - inferred resources
Table 3 Physical properties of
diatomite (on average)
Physical Test Abiyata Adami Tulu Chefe Jilla
type
diatomite diatomite
Shaking density 169g/l 162g/l 163g/l
Jolting density 260g/l 258g/l 268g/l
Block density 0.42g/cm 3 0.42g/cm 3 0.32g/cm 3
Porosity 85.6% 73.4% 76.7%
Water content 5.1% 9.7% 12.7%
If you require information on the geology
and mineral opportunities in Ethiopia,
please contact the Geological Survey of
Ethiopia (GSE):
Geological Survey of Ethiopia
P.O. Box 2303
Addis Ababa, Ethiopia
Tel. +251 6 463325
Fax +251 6 463326
Email: Survey@ethionet.et
www.geology.gov.et
We are looking forward to your mining
investment in Ethiopia.
Prepared with assistance from GEUS.
December 2010