DISCUSSION OF THE CHEMICAL ANALYSES 117 



The holyokeite, freed from water and calcite (analysis X), finds place 

 in class I : Persalane, order 5 : Canadare, rang 1 : Nordmarkose, sub- 

 rang 4 : Dosodic, and a comparison of this with the place of palagonite 

 above gives the extent of the differentiation.* On plate 32 is given the 

 graphic representation of the same differentiation. If the anhydrous part 

 of the palagonite had been calculated to 100 before using, the figure 

 would have been enlarged, so that its base would have had nearly the 

 same length as the silica line in the normal diabase. 



Theoretical Explanation of the Formation of the Holyokeite 

 and Palagonite and their Inclusions 



the general process 



The magma which had dissolved so much quartz and calcite under 

 such temperature and pressure that they could not react on each other 

 soon became unstable. When the point for the beginning of solidification 

 was reached the great feathery pyroxenes in the one variety and the 

 great poikilitic feldspars and skeletonized magnetites in the other were 

 the first to form, shooting out into the very liquid magma, and, floating 

 from place to place in it, were carried sometimes into hotter parts (the 

 very change in the magma made it a better solvent), and then in whole 

 or in part remelted. They thus sometimes inclosed large areas often 

 an inch or more on a side wherein the differentiation and solidification 

 took place in many separate interstitial spaces. 



The glass is peculiar in that more than a sixth of its mass is water ; 

 more than a fourth iron. 



Nearly all the iron and magnesia are concentrated in the glass, while 

 the other differentiate (the holyokeite) is over 92 per cent albite and 

 anorthoclase (see plate 32). We must then assume a sudden differenti- 

 ation in these interstitial residua. Albite needles bristled out from the 

 cooler borders of these interstitial spaces, crystallization of the albite 

 being perhaps promoted by the feldspar surface already formed as when 

 albite forms on microline, and the quartz albite mixture filled the spaces 

 between the albite needles and thus crowded the water, iron, and magne- 

 sia toward the center to form a glass with the minimum of silica. 



FORMATION OF THE HOLYOKEITE DIKES 



In this way the differentiation into the holyokeite groundmass and the 

 palagonite was effected. Where the development of the great pyroxenes 



* The keratophyr of Fair Haven freed from H 2 and CaC0 3 in the same way finds the same place. 

 Mr Washington calculates the analysis as it stands to the same class and ox-der and to rang 2 : 

 Pulaskase and subrang 5 : Persodio, 



