PHILIPPINE RAW CEMENT MATERIALS. 



221 



tween the fingers, or gently in a mortar, 

 be seen from the following numbers : 



The state of suljdivision will 



Sie%'e. 



Per cent. 



1 



Size. 



Meshes 



per 

 centi- 

 meter. 



Passed. 



Not 

 passed. 



100 

 80 

 GO 

 50 

 ■10 



40 

 32 

 24 

 20 

 16 



45 

 57 

 76 

 94 

 98i 



55 

 43 

 24 

 6 



14 



A large formation of schist occurs on the Island of Eoniblon; this is 

 so high in silica that it is doubtful if it could be used alone for the 

 manufacture of cement, but a small amount of material of this nature 

 could successfully be employed for recomposing the ordinary clay or shale 

 base. 



It is not improbable that highly siliceous materials similar to those 

 in Eomblon occur along tectonic lines and if so, then possibly a similar 

 schist more available to Cebu, might be found on some of the smaller 

 islands lying nearer to it. In fact, schists have been found on Cebu 

 itself. These occur and outcrop only in a few places along the Cordi- 

 llera under the capping. One such schist has been described as rhyolite 

 by H. G. Ferguson.-^ 



Analyses of these materials rich in silica are given in Table VIII. 



Sample No. 8. Sandstone which outcrops above the coal at the Compostela 

 mine. 



Sample No. 9. Average of two analyses, agreeing fairly well, of independent 

 samples taken from the schist formation near Eomblon, Eomblon. 



Sample No. 10. Cebu rhyolite. 



Tabus VIII. — Analyses of materials rich in silica. 

 [The numbers give percentages.] 



Constituent. 



Silica (SiO.,) 



Alumina (AloOj)" 



Iron oxide (FenOa)'' 



Lime (CaO) 



Magnesia (MgO) ___ 



Potash (KoO) 



Soda (NasO) 



Loss on ignition 



Water (H2O) below 110°C. 



72.76 

 15.58 

 1.42 

 0.62 

 Trace. 



3.53 

 1.84 



80.12 

 12.56 

 1.15 

 0.12 

 0.48 

 2.38 

 1.31 

 1.94 

 0.21 



67.25 

 13.12 

 0.24 

 1.23 

 1.10 

 4.38 

 0.59 

 6.11 

 6.15 



"^Includes possible titanium oxide (TiOa). 

 "J Total iron determined as ferric oxide. 



--This Journal, Sec. A. (1907), 2, 408. 



