426 A. B. Lyons — Composition of Hawaiicm Soils. 



mountains of Oahu) ; a somewhat vesicular stony lava of 

 rather light color, porphyritic with white crystals of feldspar. 



JS^o. 6 is a type which I have seen nowhere but on the island 

 of Oahu, and chiefly in the oldest formations of that island, 

 viz: in the Waianae mountains. I should expect to find it 

 also on Kauai, but that island I have -not explored. It i& 

 highly feldspathic and made up largely of tabular crystals 

 5 to 1 S"""" long and perhaps 1 or 2""^ thick. In superficial por- 

 tions of the rock, the augitic constituent of the lava is often 

 partially disintegrated, but the specimen analyzed was quite 

 sound. It is especially remarkable for the large proportion it 

 contains of titanic acid. Previous analyses of Hawaiian lavas, 

 1 may remark, seem not to have given due attention to this 

 constituent, which in some of them is not even mentioned. 



ISTo. 7 is a close-grained dark basalt with a few green crystals 

 of chrysolite, from one of the oldest formations of Oahu. 

 Although taken from a fragment that had been detached from 

 the cliff and had lain for ages where it was submerged at 

 spring tide with salt water, it seemed to have suffered abso- 

 lutely no change, except superficially, and it may be regarded 

 as a representative specimen of this ancient trap-like basalts 

 Copper, which is present in all the Hawaiian lavas examined, 

 reaches in this a maximum figure — nearly half of one per 

 cent of CuO. 



No. 8 is another representative sample from the lowest bed& 

 of the Koolau range of Oahn. It is somewhat vesicular, and 

 has suffered some change probably in the oxidation of a por- 

 tion of its ferrous iron, and possibly in the loss of some of its 

 potash — I think not to any great extent. This, as well as the 

 preceding specimen, contains chromium, which may have been 

 present in traces in some of the other lavas, as it is not un fre- 

 quently present in the Hawaiian soils. 



No. 9 is the capillary form of lava known as Pele's hair. 

 Of course it is simply the lava of Kilauea spun into fine 

 threads and so instantaneously cooled. The sample analyzed 

 was, however, not a representative one, for it had been a long 

 time exposed to the sulphurous vapors from Halemaumau, the 

 result appearing in the analysis in its extraordinary content of 

 sulphate. We call to mind in this connection the incrusta- 

 tions, about fissures in Kilauea, of ferric sulphate, and the 

 stalactitic deposits of sulphates of soda, calcium, aluminum 

 and even of copper (curiously enough not often of iron) found 

 in caverns in the crater. 



Table III gives the result of analyses of specimens of rock 

 altered by exposure to the weather, and of volcanic tufa. In 

 the former, while titanic acid seems to have been but slightly 

 diminished in amount, there has been a notable loss of silica, 



