1 84 The American Geologist. September, 1905 
Fig. 1. Development of calcite crystals from Grand Rapids, 
Michigan. The angles which determined the forms were as follows: 
Obs. 
Calc. 
Diff. 
00' (polar) 
84°23' 
84°32y 2 ' 
— 9%' 
vv' 
35°33' 
35°36' 
—3' 
TV 
29° 5' 
29° 2' 
+3' 
iblb' 
32°40' 
32°36' 
+4' 
MM' 
40° 3' 
40° 3' 

r M 
33° 0' 
32°57' 
+3' 
rw 
29°52' 
29°54' 
—2' 
r 5 
116° 0' 
115°57' 
+3' 
rl 
106° 0' 
105°59' 
+1' 
The new form Rf was found on a number of crystals 
and was accordingly determined. The form 1 was found on 
but one crystal, though here with a large development. 
See fig. 1. 
The crystals represent a number of distinct habits 
among which is the barrel-shaped type of fig. 2. There is 
also another "nail-head" type, and a very steep rhombohe- 
dral type. 
Fig. 2. Barrel-shaped type of calcite from Tiffin, Ohio. 
/'. Epsomite and Alanogen from . the Cripple Creek 
District, Colorado. These specimens which were among 
the collections of the university of Wisconsin have been 
analyzed, the first mentioned by Mr. W. O. Hotchkiss, and 
the last mentioned by both Mr. Hotchkiss and Mr. R. M. 
Chapman. Their results follow : 
^Epsomite' 1 '' from Cripple Creek District, Colorado. 
Analyzed by W. O. Hotchkiss. 
MgO 19.35 
SO 3 ' 38.51 
H 2 ' 42 . 03 
99.89 
