and the Results of its Alteration. 281 
spr an and muscovite to the eed aoc ne (which as stated 
ve we have adopted), on ae ‘i the fact that by an 
exchange of alkali and the loss two molecules of silica, 
pashan: would isl ee te 
Li, ALSi,0;5 = = gg iecte: typ 28i0. (6) i 
He remarks upon the free quartz present in the pseudo- 
morphs as evidence that this process actually went on 
It is interesting to note in this connection the following 
statement made by Mr. Julien, he says: “ Man seudomorphs 
were found in the Chesterfield vein which consist in large part 
or entirely of a greenish-yellow muscovite with peculiar greasy 
luster. In fact all stages of intermixture of cymatolite were 
observed, from the almost pure pseudomorphs of the latter 
mineral in which muscovite occurred only in minute or even 
microscopic scales lying mostly parallel to the axis of the erys- 
tal—to others in which the mica was so abundant as to have 
one Le et eae of quartz in the Seen orphs. 
e specimens we have studied the case is reversed, quartz 
is chs entirely absent, mica occurs in separate form only 
sparingly, and in the formation of the two feldspars there o 
often been an assumption of silica from some outside so 
Thus far we have said nothing in regard to one seaport 
pseudomorphous mineral—the killinite. It seems impracticable 
to give this a certain place in such a scheme as that given 
above, for the good reason that its true composition is some- 
what in doubt. It is certainly a more or less impure material, 
having the same want of homogeneity and definite composition 
that is so often observed among the minerals of the pinite 
group. The microscopic structure, and, too, the results of the 
analysis, seem to justify us in the suggestion that it m may be 
essentially a hydrous potash mica, not very unlike that in the 
cymatolite. In this case its presence is not strange, for the 
SF aka between it and the other would be more in its state 
aggregation oe in composition. The chemical process 
whi ich led to the formation of the killinite is in any case 
clear, for the ee consisted essentially in the iicecnine 
of potassium and hydrogen in place of lithium, with the loss 
of silica. It may consequently be expressed by equation (6), 
