78 BUEEAU OF AMERICAN ETHNOLOGY [bull. 52 



specimens of scoria bright-yellow spots occur here and there and may 

 possibly be due in part to admixture of iron chloride. On immersing 

 in dLstUled water clean particles from such colored patches, a distinct 

 precipitation of sUver chloride was obtained on adding silver nitrate 

 to the solution. 



Specimen 263733 contains occasional vesicle fillmgs of red earth 

 which are indurated and evidently different from the loose brown 

 earth adhering to the specimen at other points. 



On these specimens, as in the above, many of the cavities of the 

 scoriae are filled with rounded grains of various minerals, as quartz, 

 plagioclase, garnet, magnetite, and pyroxene. These grains are appar- 

 ently confined to the upper, exposed part of the scoria. In many 

 cases the lower part of a scoria specimen is covered with loess which 

 stiQ adheres to it and in which evidently the fragment was originally 

 embedded, with its surface protruding above the level of the loess. 

 In this position wind or tide may have swept the rounded particles 

 of foreign material over the scoria and lodged the observed grains 

 in their present position. Such grains may also have been gathered 

 by the scoria during water transport; the grains on its underside 

 may be so intermixed with the present loess as to be covered up and 

 not easy to separate from the finer earth. It seems probable, how- 

 ever, in the absence of field data, that the first supposition is the 

 correct explanation of the presence of these grains. 



No. 263737. This scoria after heating at 1 ,100° for 40 minutes was 

 noticeably fritted. Another fragment heated to 1,400° for 1^ hours, 

 and cooled slowly for 1 hour to 1,100° and then held at 1,100° for U 

 hours became a dark-green glass which contained a small quantity 

 of magnetite and rarely a trace of the original mineral fragments. 

 The refractive index of the glass varied greatly, from 1.505 to 1.56, 

 the more deeply brown-colored fragments having the higher refractive 

 index. 



Nos. 263721 , 263722, 263732. Specunen labels : Locality: Miramar. 

 Material: Tierra Cocida." 



These specimens range in color from brick-red to dark-brown and 

 are fine-grained, indurated earths which resemble in texture the 

 brown loess of this region. Microscopically they consist of fragments 

 of quartz, plagioclase (andesine, labradorite), microcline, pyroxene, 

 hornblende, magnetite, colorless volcanic glass, and argillaceous 

 material often deeply stained with iron oxide. The outer surface of 

 these indurated fragments is often pitted; these pits are not deep 

 but often contain rounded grains of magnetite, quartz, and plagio- 

 clase similar to the grains observed in the cavities of the scoriae. 

 They have probably been lodged in the pits by wind or wave action. 



