60 
CONTRIBUTIONS TO MINERALOGY. 
[BULL. 262. 
Material carefully purified by the Thoulet solution followed by 
repeated electromagnetic extraction, and having- then a specific gravity 
of 3.121 at 25°, gave the following results on analysis: a 
Molecular 
ratio. 
Calculated for 
the formula 
H 4 CaAl„Si,,O 10 . 
Si0 2 
Ti0 2 
AlA 
FeA -- 
FeO 
MnO 
CaO 
MgO 
K 2 
Na 2 
H 2 (ignition) 
Total . . . 
38.45 
.38 
31.35 
.86 
.10 
faint tr. 
17.52 
.17 
.23 
.06 
11.21 
1.98 
38. 34 
97 
1. 00 
1.95 
100.33 
32. 44 
17.80 
11.42 
100.00 
Titanium is not considered in the ratio because probably present as 
an inclusion of rutile or titanite. If the latter, the ratio would per- 
haps approximate still more closely to the theoretical than it does. 
The agreement with the formula deduced by Ransome and Palache 
from their rather widely differing analyses is very .satisfactory. The' 
behavior of the mineral before the blowpipe is somewhat different 
from that given by those authors, or rather their statement needs 
amplification. On first applying the ffame a splinter appears to fuse* 
easily, as stated, and there is formed a blebby glass, or on large] 
splinters a porous sinter, but this fusing is only momentary, and i 1 i| 
requires the highest heat attainable, under which the fragment emifat 
quite an intense light, to produce a further softening and rounding o: >i 
the edges. If a rather large splinter is held in the flame of the blown.) 
pipe, or in a small flame of a blast lamp, a very sudden and markec 
exfoliation is observed, but even the extruded points and edges do no 
fuse complete^ in the highest attainable heat. The semifused surface 
however, appears dark on cooling, sometimes nearly black where th< 
heat was most intense. In producing this exfoliation, if care is take) 
to apply the flame but for a moment, it has been noticed that a singu 
larly shaped excrescence ma} T shoot out from a point of the surface* 
a Concerning this purified material, Doctor Ransome reports as follows: 
"I should say the material is as pure as it is possible to get it. The grains are all lawsonite, bi 
vary in individual purity. Some are perfectly clear. Others have minute inclusions, which appef 
in most cases to be solid particles but are too minute for identification. One of them, however, Wi »j 
suggestive of rutile. Some of the grains are slightly clouded with a yellowish stain which the nncr j 
scope is unable to resolve into distinct particles. There are apparently a few fluid inclusions also 
