DEC, 1908. MINERALOGICAL NOTES 
VIVIANITE 
SIPVERseUDY, 1DAH® 
163 
A crystal of vivianite of unusual size and transparency, Mus. No. 
M 9454, from Silver City, Idaho, was received from Maynard Bixby. 
The crystal, attached to a group of small quartz 
crystals, constitutes the only specimen of the 
occurrence known to the writers. This crystal 
is transparent and dark-green in color by trans- 
mitted light but by reflected light in certain 
positions appears azure-blue. It is prismatic 
in habit and elongated both in the direction of 
the c and } axes. Its length in the direction of 
iiemreaxicmis 3.5 cm.,in that of the b axis 1.7 
Goeeatgni) that of the a axis-1:1 cm. It is. 
completely developed except for the termina- 
tions of one end of the vertical axis. Measure- 
ments made partly with the reflecting and 
partly with the contact goniometer show the 
following forms and angles :— 
ettoo a (010),,% (110), w (ory, v (111). 
= 
m 
X\ 
Fic. 6. Vivianite. 
Observed Calculated 
a@Am = (100) A (110) = Hie Eyer Rik ans Or 
Gey. os. (loo) A (ior). = eGo E401 4o. 
fe | (oto) A (i1t) = reek Goss: 
The development of the crystal is illustrated in the accompanying 
figure, Fig. 6. 
