Note on Spodumene from Namaqualancl. 
67 
light vibration directions. Experiments carried out on a highly poHshed 
orthopinacoidal surface by means of the Abbe refractometer gave values 
for /3 and y of 1'670 and 1 679 respectively. From a clinopinacoidal 
surface the value a = 1'651 was obtained. 
For the above determinations sodium light was used ; the temperature 
was 22° C. 
All three varieties give a marked lithium flame reaction. Under the 
blowpipe they become white and opaque, swell and eventually fuse ; in 
the microcosmic salt bead they give the reaction for SiOa. 
One of us (G. C. S.) has undertaken to make quantitative chemical 
analyses of the different varieties, the results of which will be published 
in a later paper. 
