and the Results of its Alteration. 267 
hand, the fact that it ao ds so readily into muscovite, and 
has the same ratio as the mal varieties of that species, 
might seem to place it near ad but it certainly has no mica- 
ceous structure. The true lithia mica (lepidolite) has a very 
different composition. 
2. Cymatolite. 
The name cymatolite was given in fated by Prof. oo to 
a mineral found at Goshen and .- ich, Mass., sult of 
the decomposition of spodumene. The ainiven given a him 
left the composition of the supposed new mineral in pect 
and this doubt was not removed by a subsequent analysis by 
r. B.S. Burton. Mr. Julien gives in his paper several anal- 
yses of cymatolite which agree well together and which corre- 
spond to a simple chemical formula. In our earlier investiga- 
tions we assumed it to be an established point that the species 
was a good one and had a definite composition. This assump- 
tion was confirmed by two closely agreeing analyses (given be- 
low) made upon the Branchville material. Further study, 
however, which was made necessary by the results reached in 
the case of 8 spodumene—for the cymatolite is directly derived 
from the 8 spodumene—has convinced us that the supposed 
species is i a a remarkably uniform and intimate mechanical 
mixture of muscovite and albite. We shall, however, through- 
out this paper retain the name cymatolite as a convenient way 
of designating this interesting aap cnc substance, and shall 
describe it first as if it were a true specie 
The physical characters of the coanaciiie of Branchville 
are as follows :—It has a distinct fibrous structure, sometimes 
strai edly but more generally wavy. It is also at times con- 
i ly fibrous and again scaly. The specific gravity = 2°692- 
- The color is gore white, 5 t it - often slightly 
Fablowd and occa gh it has a faint pin 
in an intricate hte giving sometimes a feather-like appear- 
ance. biotrer all trace of the original prismatic spe: and 
cleavage of t e spodumene has disappea cases, 
however, in a interior of a crystal this longitudinal inencters 
is still apparent, although the direction of the fibers remains 
transverse. (Compare also other figures in the Plate, in which 
¢ = cymatolite.) 
