358 
CEMENT MATERIALS AND INDUSTRY. 
[BULL. 243 
obtained b}^ the Greek colonists, and at a later date by the Romans 
The material has also been exploited at other points near Rome anc 
Naples. 
Most of the Italian pozzuolana is obtained from small open cuts oi 
pits, though some of these workings are now of great depth. Thosd 
of Trentaremi, for example, are about 600 feet deep. The varioif i 
deposits differ greatly in the quality of the materials obtained from 
them. Care should therefore be exercised in selecting a spot fon 
exploitation, and soiling of the material dug would be advisable it 
order to keep the product of uniformly high grade. After extraction 
the material is screened and ground. In addition it is occasionally 
slightly roasted to increase its hydraulic properties. Carelessness 
both in the mining and in the later preparation of the pozzuolana, ha; 
brought the Italian article somewhat into disrepute among Europeajj 
engineers. In consequence it is losing ground with respect both t( 
pozzuolana from the Azores and to trass from Rhenish Prussia. 
Pozzuolana has been shipped from San Miguel, in the Azores, t< 1 
Portugal for over a hundred years, and has been used with very satis J 
factory results in many important buildings, harbor works, etc. Th< 
Azores pozzuolana varies in color from yellowish to brownish, ai 
sometimes to greyish. It is frequently so fine grained as not t< 
require screening or grinding before use. A reddish-colored variety 
from the same islands is termed tetin. 
The following analyses of pozzuolana are fairly typical of its rangt. 
in composition: 
Analyses of pozzuolana, Italy. 
Silica (Si0 2 ) 
Alumina (A1 2 3 ) 
Iron oxide (Fe 2 3 ) .. 
Lime(CaO) 
Magnesia (MgO) 
Alkalies (K 2 0, Na 2 0) 
Water, etc 
52.66 
14. 33 
10. 33 
7.66 
3.86 
4.13 
7.03 
60.91 
21. 28 
4.76 
1.90 
.00 
10.60 
n. d. 
:: 
56.31 
15. 23 
7.11 
1.74 
1.36 
11.38 
6.12 
44. 
15. 
12. 
8. 
4. 
5. 
9. 
Trass, another puzzolanic material of commercial importance, i 
found in the districts bordering the Rhine in Rhenish Prussia. Th.li 
towns of Brohl, Kruft, Plaidt, and Andernach, all about 10 to 15 mile 
southwest of Coblenz, are the principal points near which the materia 
is worked. Trass is an ancient volcanic mud composed of a ground I 
mass of volcanic dust, in which fragments of pumice, volcanic rocks- 
etc., are embedded. 
