398 
REPORT OF CHRMIOAE LABORATORY 
Lime from 
coral at Port 
Sudan 
Deposits of 
gypsum 
Analysis of 
gypsum 
The coral formation on which Port Sudan is huilt produced a fat lime of good quality. 
The analysis of a sample furnished by .Mr. 0. E, Dupuis, Inspector-General, Sudan 
Irrigation Service, gave results as follows ;— 
Calcium carbonate ... 
Calcium sulphate 
Jlagnesiuin carbonate 
Ferric oxide and alumina 
Silica ... 
Water (free and condiined) 
85-90 per cent. - 
5-67 ,, 
1-28 
MO 
1-48 
3-9C 
Tot,\l ... ... 99-.39 
Gypsum Deposits. Red Se.\ Province 
At the present time, the cost of plaster of Paris is so high in the Sudan that very 
little is used in building construction. The discovery of a deposit of gypsum at Gebel 
Tetawib, about one hundred miles north of Port Sudan, to which attention was called by 
Mr. C. Crossland, Marine Biologist, is therefore of interest. The deposit, which appears to 
be of considerable extent, is in some places at least 15 feet thick, and the outcrop is within 
a few hundred yards of a sheltered harbour. 
Analyses of four samples of the rock were made, with results as follows : — 
Upper 
portion 
Middle 
portion 
Lower 
portion 
Middle of 
S.W. end 
Insoluble (silica, etc.) 
0-89 
1-70 
0-C4 
0-72 
Ferric oxide and alumina ... 
n..3C 
0-48 
0-40 
n-40 
Calcium carbonate ... 
o-n:? 
1-88 
1--20 
n-.38 
Sodium chloride 
— 
0 -ir. 
0.08 
o-oo 
True gypsum (by difference) 
...j 98.12 
or)-8o 
97-73 
98-44 
Gypsum in masses of small crystals is also found in quantity a few miles south of the 
above, on the Rawaya peninsula. The composition of a single sample was as follows ; — 
Insoluble matter (sand, etc.^ 
1-15 per cent 
Ferric oxide and alumina 
. n-34 
Calcium carbuiiate 
. Im3 
Sodium chloride ... 
. 2-.7;') 
True gy})snm (hy difference) 
. 94-43 
Either of the above deposits would furnish, if jiroperly treated, a plaster of Paris of 
good (juality. 
