Dec, 1908. 



MlXERALOGICAL NOTES 



163 



VIVIANITE 



SILVER CITY, IDAHO 



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 b axes. Its length in the direction of 

 the c axis is 3.5 cm., in that of the b axis 1.7 

 cm., and in 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: — 



a (100), b (010), m (no), w (Toi), v 



The development of the crystal is illustrated in the accompanying 

 figure, Fig. 6. 



