20 J. M. Blake on Hortonolite. 
2. Observations on the crystalline form, optical geisha 
and ere of Hortenolite; by Joun M. Bria 
nation is not yet completed, but it being desired that a descrip- 
tion of this mineral should be furnished as soon as possible, the 
results must be given in a form that will require the least expla- 
nation, For the} present purpose, the symbols of Des Cloizeaux 
the figures in his mineralogy. It will be noticed that the 
“vertical prism” is differently tasted. 
The il planes on this variety, are : h',g’,e', a’, g?, 
63 and y; or in Dana’s symbols: O, 7-7, 7-2, 1-7, 1-7 1G aa ta 
A dent of some foreign substance had destroyed the 
brilliancy of the planes, and this could not be entirely removed 
so that they would give perfect reflections ; and, besides this, 
some pers of crystals appear to have been originally rounded. 
Fig. 1 is proportioned from some of the larger crystals. 
They were partially imbed- 
ded, so that but a portion of 
the ” planes could be distin- 
uished on any one of them. 
he intersections with the 
other planes satisfactorily ie / 
termined the planes 02, 4 
these particular crystals. 
ig. 2 is a common form of — 
the medium-sized crystals. — 
The upper planes on the front side, can be explained as the 
pine 7. The or eel 3 their intersections with e. and an ~ 
roximate measurement of their inclination on g' leaving 
little doubt of their identity with this Pe ane. The goniometer 
readings were as follows on this crysta 
For the prismatic zone: pistes s : a 35’; et, 116° 15; 
areal y 
wis J 3 
For zone 2, Ree the front upper planes: 0°; 7, 78° 
to 80°; 1, 100° 0 1015 9 its pe lanes! 9, 051, 
Zone 3, including the upper planes: g', 0°; 63, 69°; 
@', 90°? "ba, 110°. : 
“tats Bes ee ee 
