LAGXJNA CLAYS. 



379 



A light gray sample of fair quality was taken from the lowest outcrop. 

 Three determinations gave its tensile strength as 4.8 kilograms per 

 square centimeter (68. 3 pounds per square inch) and its air shrinkage as 

 1.4 per cent. 



Continuing up the Butadero Elver, on the left there is a large outcrop 

 of clay about 3 meters wide and 4 meters high just above the high-water 

 line. On the surface it is bleached fo a whitish color, Jjut a few centi- 

 meters below it is blue. This clay contains pyrites and grit which unfit 

 it for potter}^ use in the raw state. A short distance farther up, the 

 Sunlva Sunlca and the Kaloong Elvers join to form the Butadero. About 

 a half kilometer up the Kaloong on the right is a perfect illustration of 

 the breaking down of the basal rock in the formation of residuary clay 

 deposits, but the decomposition of the deposit has not continued far 

 enough to form any considerable quantity of good clay. On the ridges 

 the decomposition is veij incomplete and the clay is full of unweathered 

 rock fragments and pyrites. In the water channels and moist places 

 the decomposition is fairly complete, but these areas are neither large 

 nor numerous. However, a sample from one of these places was the best 

 that I found in the Matiquio region, and when subjected to laboratory 

 examination gave the following results : 



Chemical analysis. 

 [Figures give percentages.] 



SUica 

 (SiO.). 



Alu- 

 mina 

 (AI0O3) 



Fluxes. 







Tita- 

 nium 

 oxide 

 (TiOo). 



Sul- 

 phur. 



Total 

 fluxes. 



Total 

 iron 

 given 



as 

 ferric 

 oxide 

 (FeoOs) 



Lime 

 (CaO). 



Mag- 

 nesia 

 (MgO). 



Soda 

 (NaoO). 



Potash 

 (K.O). 



Loss 

 on igni- 

 tion." 



Water 

 (H„0) 

 below 

 110°. 



61.00 



19.71 

 i>20.96 



3.48 

 "3.70 



0.34 

 i>0.36 



0.07 

 bO.07 



0.23 

 bO.24 



0.61 

 K0.65 



8.18 

 1-8.70 



5.97 

 i>0.00 



0.95 

 '1.01 





4.73 

 "5.02 



» Mostly water above 110°. " Recalculated free from water below 110°. 



Physical properties. 



Water 

 added to 



give a 

 workable 



paste 

 (per cent 



total 

 weight). 



Tensile strength. 



Shrinkage (per cent). 



Color. 



Air dried. 3 de- 

 terminations 

 averaged. 



Burned, 4 de- 

 terminations 

 averaged. 



Air. 



Fire, 



at cone 



No. 9. 



Total. 



Air dried. 



Burned with 



free access 



of air. 



Kilos 



per 



square 



centi- 

 meter. 



Pounds 



per 

 square 

 inch. 



Kilos 

 per 

 square 

 centi- 

 meter. 



Pounds 



per 

 square 

 inch. 



22.4 



3.47 



49.3 



9.07 



129 



4.7 



-1-0.4 



4.3 



Light gray ___ 



Light gray. 



