A BRIEF REVIEW OF INDUSTRIAL MINERAL OF DJIBOUTI REPUBLIC

Report
REPUBLIC OF DJIBOUTI
MINISTRY OF ENERGY,IN CHARGE OF NATURAL RESOURCES
Presented
By
ABDOURAHMAN OMAR HAGA
PRESENTED BY ABDOURAHMAN OMAR HAGA
Djibouti
A) INTRODUCTION
 Industrial minerals mean any rock or mineral of
economic value excluding hydrocarbons and metallic
ores. In fact, almost any naturally occurring mineral
substance which can be used for the need of industry,
whether large scale, small scale or artisanal is
considered as industrial mineral.
 The Djiboutian economy is mainly based on the
tertiary sector. The service sector exceeds the
industrial, the agricultural and mining sectors.
 The agriculture is mainly subsistence farming with
some large farms where products are sold at Djibouti
town.
 The industrial sector is dominated by small scale
manufacturing (water, beverage and other consumable
product.
The mining sector is represented by:
- Salt extraction
- Brick manufacturing
- Sand, gravel exploitation
- Crushed stone (basalt), cutted
stone for building,
.
The inventory of industrial minerals was not done
properly during the geological mapping of the country
(1982 to 1996).
But with the several scientific research publications
done by local and foreign scientists, it is possible to
give a brief and generalized overview of industrial
minerals of Djibouti.
This report attempt to give a brief and generalized
overview of the utilization of industrial minerals in
RDD.The second part of the report present a summary
of the industrial minerals resource of RDD .
B)GENERAL GEOLOGY
Djibouti is at the junction of three rifts (east African, red
sea, Gulf of Aden).
Volcanic formations cover a large percent of the country.
The oldest rocks (Mesozoic sediments) crops out in
the southern part of the country.Endoreic plains,
grabben and coastal plains are filled by tertiary to
quaternary sediment.
The volcanic rocks of Djibouti are mainly basalt and
rhyolite (bimodal volcanism).
The following series are recognized:
 adolei basalt(22 to26 my)
 mabla rhyolite(15 to19 my)
 dalha basalt(4 to 9my)
 stratoid basalt (1 to 4 my)
 gulf of tadjoura basalt (1 to 3 my)
 recent basalt(rifts)
Geological map of Djibouti
These basalt and rhyolite are often altered by hydrothermal
fluid; they may contain a variety of metallic minerals
deposited by geothermal water (gold copper, lead, zinc,
manganese….)
.
Mesozoic sedimentary are recristallized by dike intrusion,
several mineralization are noted by geologist but not
fully explored.
Tertiary to quaternary sediments of lacustrine, marine
origin are widespread in endoreic plain, grabben and
coastal plain; exploitable clay, gypsum, diatomite, salt,
sand, gravel ….are recoverable from those sediments.
C)MINERAL PRODUCTION AND
TRADE
 The only documented information on export of
industrial minerals concern the salt of Lake Assal
exportation to ETHIOPIA (1999 to 2003) (fig 1, fig 2)
YEARS
PRODUCTION(tonnes)
1999
127283
2000
135933
2001
173099
2002
162266
2003
128494
TOTAL(1999 to 2003)
727075
Salt production (1999 to 2003)
salt production
180000
160000
140000
120000
100000
80000
60000
salt production
40000
20000
0
1999
2000
2001
salt production
2002
2003
The decline of the production of salt from Lake Assal is
mainly due to the arrival of new salt product in the
Ethiopian market and certainly a reorganisation of
several companies.
Others industrial minerals: clay, gravel, crushed basalt,
building stones are exploited in the vicinity of the
capital
It seems that some cutted bock of basalt and rhyolite are
exported. Near Djibouti town a brick making factory
use the residual clay from the alteration of the Gulf of
Tadjoura basalt .Sand and gravels for aggregate
purpose are exploited all over the country from wadi
bed .
In 2009, an exploitation license for a perlite deposit was
delivered by the MERN to JB JIBOUTI MINING LTD,
the exportation of Egerleyta perlite was estimated to
be of 50 000 tonnes per years .
 The lack of systematic record of mineral production,
consumption and trade, overshadow the contribution
of mineral sector to the economy.
The republic of Djibouti import several mineral raw
materials and products:
 ceramic products(pipe, tile, cement, clay based
refractories)
 roofing tiles
 chalk, pigments
 cement product
 Abrasives….
The high costs of imported product are likely
to encourage development of indigenous
resource in the future
D)INDIGENOUS INDUSTRIAL
MINERALS
1) Construction raw materials
 Basalt, rhyolite, trachyte, sandstone,
limestone can lend to the production of a
wide variety of cut and polished stones.
 Sand and gravel used today are from wadi
bed, marine sand have never been exploited.
 Abundant sand, gravel can be recovered in
graben (HANLE, GAGGADE….)
2) Clay
Several deposit of clay is encountered:
 clay from alteration of basalt
 lacustrine clay
 clay deposited in endoreic plain
All these clay must be studied to determine their
suitability in different end uses.
Bentonitic clay is present in the graben of Hanle (it
was used by a drilling company (GENZEL) during
gradient wells drilling).
3) Gypsum
Thick and extensive resource of gypsum are found
around the LAKE ASSAL.Other deposits of gypsum are
noted as intercalation in Jurassic limestone of Ali
sabieh.The gypsum deposit of Assal is huge (millions
of tons).
4) Limestone
 Slightly metamorphosed limestone of Ali sabieh is a
potential target for decorative and semi-precious
stone.
 Travertine deposit (thermal spring calcareous deposit)
are seen in Hanle ,lake assal ,lake Abbe,allol…
 Jurrassic limestone suitable for cement oucrop in the
Ali-sabieh area(cement factory project in progress)
5)Pumice, pozzolane, scoria
 Abundant resources of scoria are widespread in the
stratoid basalt, the gulf of Tadjoura basalt, recent
basalt (Assal, Manda inakir).
 Volcanic cones composed of scoria and pozzolane are
visible at the southern part of Djibouti town.
 Pumice flow and fall are sometimes associated to the
terminal rhyolitic extrusion of the stratoid series
(southern part of Assal rift).
 Pumice is also found in the rhyolitic series of mabla.
6)silica sand and quartz
 The cretaceous sandstone of Ali sabieh are
source of silica sand but proper evaluation
must be made to determine their suitability
for various end uses.
 Quartz gravel and sand cover large area at
Assamo and south of Ali adde (suitable may
be for ceramic manufacturing or glass
manufacturing).
7) Salt
 Salt of lake assal is a resource of considerable
importance; it is a renewable resource (the lake is fed
by the sea from fractures).SALT-INVEST a Djibouti
American company have the exclusive permit of
exploitation of the salt .
8) Soda ash
 Elevated content of sodium carbonate are signalled in
Lake Abbe.The quantity and quality of the soda ash
deposit of Lake Abbe must be evaluated properly.
9) Diatomite
 In gobaad, hanle, gaggade, assal… calcareous and
diatomite deposit cover great surface; strata of pure
diatomite (1 to 5m) are intercalated in more calcareous
levels.
CONCLUSION
 Until know, limited effort was expended to explore
industrial mineral resource of Djibouti.
 The resource already identified suggests that
enormous undiscovered mineral potential exist in the
republic of Djibouti.
Satellite view of assal Lake
Lake ASSAL
salt
MERCI DE VOTRE ATTENTION

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