and the Results of tts Alteration. 275 
in addition there appear to be scales inclined at equal angles in 
opposite directions on either side of each parallel line. They 
exert a considerable action on polarized light. Most of the 
specimens are of so fine a texture as not to allow of satisfactory 
resolution. One section, however, which was somewhat coarser, 
seems to offer an explanation. This one appeared to consist 
mostly of minute scales having all the appearance of mica 
These scales were strikingly similar to those of unquestioned 
character formed from the alteration of eucryptite and illus- 
trated by fig. 19. ister seems to be but little doubt that this 
is the true resolution of the mineral. In addition to these 
scales, there are small portions which do not polarize light, 
ich may be amorphous silica, and occasional other particles 
less easily defined. 
The idea of a relation, between the minerals of the pinite 
group and those potash micas which yield water on analysis, is 
not a new one, but was long since advanced. It is recognized 
by Profess or J. ~ Dana, in the 5th edition of his System of 
Mineralogy G8 (186 
If analysis 1 of killinite be co ot ia with the composition of 
muscovite on p. 272, and also with the analyses of muscovite in 
Dana’s Mineralogy, 5th edition, the correspondence will be at 
once recognized. The variation of analysis 2 of killinite 
would be explained by supposing the presence of several per 
cent of free silica; the correspondence would then be quite 
close. Moreover, ‘the observations with the microscope have 
made wna seems plausible, although the want of peat 
homogeneity in the ki 
definite formula. 
7. Pseudomorphs of Vein-granite. 
We employ the same term, as Mr. Julien, to describe certain 
pseudomorphous crystals of spodumene, which consist of a 
more or less coarse agglomeration of feldspar (albite and 
microcline), and mica. In such cases, which seem to be rarer 
at Branchville than at Chesterfield, the constituent minerals 
are well developed and have the same character as in the vein 
as a whole. e feldspar, for example, is not granular and 
without apparent cleavage, as is generally true of the special 
cases before described ee occurs in rather broad cleavage 
fi ents. he surfaces of these crystals are very rough, 
often covered with rosettes of albite, and yet the general form 
of the original spodumene can always be distinctly seen. It is 
to be noted that quartz is almost entirely absent in these com- 
