Mineral Resources Potential - Geothermal Resources

162 M i d Resources Potential of Ethiopia
sizes and shapes can pass through), as traps for molecules so they
can be andyzed. Zeolites have the potentid of providing precise
and specific separation of gases including the removal of H2Q,
C02 and SO2 from low-grade natud gas streams. Other
separations include: noble gases, N2, freon and formaldehyde.
However, at present, the true potential to improve the handling of
such gases in this manner remains unkmwn.
Currently, the world's annual production of natd zeolite
is about 4 million tons. Of this quantity, 2.6 million tons' are
shipped to Chinese markets to be used in the concrete industry.
Eastem Eumpe, Western Europe, Australia, and Asia are world
leaders in supplying the world% demand for natural zeolite, By
comparison, only 57,400 mettic tons (wurce: U.S. Geological
Survey, 2004) of zeolite (only 1% of tke world's cmmt
production) is produced in North America+
Natural zeolites form where volcanic rocks and ash layers
m t with alkaline groundwater. Zeolites also crystallized in postdepositional
environments over periods ranging from thousands to
millions of years in ~Ilow marine basins. Ndly occurring
zeolites are rarely pure and are contaminated to varying degrees by
other minerals, metals, quartz or other zeolites. For this m o ,
naturally occurring zeolites are excluded from many important
commercial applications where uniformity and purity are essential.
Natural eeolite deposits in Ethiopia
Several million tonnes of high-grade zeolite deposits (mordenite
and clinoptilolite) were discovered by geologists of the Ethi*
Canada agrogology project in rift valley sediments nmr Nmth
and Boru, west of N mth, Muger and Gondar (Fig. 37). Zeolites
have high cation exchange capcities and, specifically, high
ammonium selectivities. There we many applications of zeolites in
agriculture and horticul~, among them are applications of
zeolites in chicken houses that can reduce the losses of