258 J.P. Cooke, Jr., on Childrenite from Hebron in Maine. 
Art. XXVI—Crystallographic examination of the Hebron min- 
eral, and comparison of it with the Childrenite from Tavistock ; 
by J. P. Cooxg, Jr. 
THE measurements, which I have made of the crystals from 
Hebron, sent me by Professor Brush, have afforded the follow- 
ing results. . 
Form trimetric.— Ratio of axes 
a:6:¢ == 0977 21: 1482. 
Observed. Calculated. 
1 onl (mac.) 129° 30’* 
1 on 1 (brach.) 101° 36’ 
nl 99° 997 
on 2) 127° 10’* 
2ton 2t(over O) 74°20’ 74° 227 
For comparison with the above, I have made the oe 
in 
m ements and figure of the childrenite of Tavistoc 
Devonshire, England. 
2. 
Ratio of axes—a: 6: ¢ == 0°969: 1: 1-498. 
Observed. Calculated. 
1 onl (mac) 180° 10/* 
1 onl (brach.) 101° 43’* 
1 (basal) 98° 44’ 98° 40 
2% on 2% (over O 24’ 
The values asterisked are in both cases those used in caleu- 
lating the angles given in the second column. The faces 1 and 
u 
crystals of the Tavistock childrenite were examined, and the 
same angles on the different specimens of the same kind were 
found to agree very closely with the values given above in the 
amined, on account of the striation just noticed. Alt 
ough there — : 
is a difference of over half a degree in one of the fund a 
AMC tat 
crystals are a variety of childrenite, differing per from 
English igi de fe scan tik Pacidainntal SP of oben 
composition, 
