81 
TAB. CCXLI. 
SILEX ett eua. 
Crystallized Quartz. 
Class 2. Earths. Order'1. Homogeneous. 
Gen. Silex. Spec. 1. Quartz. 
Div. 1. Crystallized. 
Tus curious specimen was collected long since by our 
late worthy friend Mr. W. Day, in Derbyshire; and as we 
have not seen the like elsewhere, we consider it as a va- 
luable specimen. It is not uncommon to see Quartz on 
Galena; but when it occurs in eighteen-sided crystals fairly 
terminated at both ends, the prism elongated, and mostly 
perpendicular upon all the faces of the Galzena, whether the 
Galena be cubical or octaédral, it is very remarkable. In- 
deed the Quartz in general appearance resembles small seed 
or grains, which, when perfectly well crystallized, are not 
common. They are sometimes dispersed, though adhering 
in bundles to each other, as figured at the bottom of the 
plate, and occasionally terminated by three-sided summits. 
VOL. III. G 
