129 
TAB.-CCLXV. 
SILEX Mesotypus. 
Mesotype. 
Class 2. Earths. Order 1. Homogeneous. 
Gen. _ Silex. Spec. 
Div. 1. Crystallized. 
Syn. Zeolithes figura determinata crystallizatus. Wal. 
ler Ne 325. 
Zeolithes. Cronst. 108—112. 
Zéolithe en hie prismatiques ou pyramidales. 
De Lisle, 2 : 
Argile unie a ie Se silicieuse, faisant la moitié 
du poids, et quelquefois davantage, et 4 un 
peu de chaux. Zéolithe. Sciagr. 1. 301. 
Zeolith, Emmerl.1.199. Wern. 1. 265. 
Zeolite. Kirw. 1. 278. 
La Zéolithe. Brochant, 1. 298. 
Mesotype. Haity, 3. 151. 
Perruars it is one of the most curious phenomena in 
Nature, that in the craggy Trap Rocks which include so 
many substances, most of them seem to be passing into new 
appearances, as if having been of different composition or 
differently acted upon by confined agents continually work- 
ing. Thus Quartz, Chalcedony, Hyalite, Analcime, Cha- 
-basie, and the present substance, with some others, some- 
times fill a number of spaces, or line them, or are crystal- 
lized in various ways. In this instance the crystals are un- 
commonly interesting, being so like one distinct substance 
passing out of another, that it has been compared to crystals 
passing out of shells, the cavity they pass from being often 
coated with a substance outwardly resembling a pebble 
fitting the unequal hollow, and itself hollowed by decome 
VOL, III. K 
