60 
MUSEUM BULLETIN NO. 27. 
Several analyses were made of the lilac crystals, with the following 
results: 
Analyses of Lilac Crystals of Vesuvianite. 
SiO, 
Ai s O, 
FejOi 
CaO 
MnO 
MgO 
1 
36*67 
20*35 
1*01 
37*35 
0*18 
2*49 
2 
36*74 
19*95 
0*60 

3 
36*94 
19*95 
0*87 
0*21 
4 
36*72 
20*07 
0*82 
37*59 

5 
37*31 
19*83 
0*97 
37*90 
0*29 
1*85 
Mean . . . 
36*88 
20*03 
0*85 
37*61 
0*23 
2*17 
In each case the total iron present has been calculated as Fe»0*; 
no seperate determination was made for ferrous iron. The water was 
estimated indirectly from the loss in weight after heating; at 105 degrees 
C. this loss was 0*03 per cent and there was a further decrease of 3*06 
per cent after prolonged ignition. A second determination on another 
selected sample gave a total loss in weight of 3*33 per cent. The mean 
of the above analyses is given in column 2 in the following table. The 
specific gravity of the lilac crystals is 3*32. 
A single analysis of the pale yellowish-green crystals from the 
Montreal chrome pit gave the result shown in column 3; as will be noted 
there is a close correspondence in the composition of the two varieties, 
the only essential difference being, that in the yellowish-green crystals 
about 4 per cent of the Al 2 Oa has been replaced by its equivalent of 
Fe 2 0,. 
Analyses of Vesuvianite . 
Calculated for Clarke’s 
formula 
Lilac 
crystals. 
Yellowish-green 
crystals. 
SiO, 
36*96 
36*88 
36*62 
AUO, 
20*94 
20*03 
15*96 
Fe*Q*. ......... 
FeO 
0*85 
4*30 
0*54 
38*66 
trace 
1*25 
0*07 
CaO. .......... 
MnO, .... 
MgO........... 
HjO— 105°C 
40*25 
37*61 
0*23 
2*17 
0*03 
H,O+105°C.... 
1*85 
3*06 
3*11 
100*00 
100*86 
100*51 
Analyses of vesuvianite do not, as a rule, lead to any simple formula 
for the mineral, and specimens from different localities may vary consider- 
ably in composition. It is, broadly speaking, a calcium-aluminum 
silicate, in which varying proportions of the calcium may be replaced 
by equivalent amounts of other metals, especially magnesium and ferrous 
