142 
We do not know that this has been before noticed, and 
it is very rare at present. The modification of the Stron- 
tian indicates a centre, and the crystallizations seem to 
meet in the middle somewhat in points ; but whether this: 
lined a cavity on the inside of a fissure or vein I know not, 
nor does it often happen that the workmen are very parti- 
cular in this respect ; but metals of some kinds may be said 
to indicate veins or lodes, which are nearly the same 
thing. 
