TAB. LVIII. 



SILEX Analcimus, var. fibrosus. 



Fibrous Analcime in Trap. 



Class 2. Earths. Order 1. Homogeneous. 

 Gen. 4. Silex. Spec. 8. Analcime. 



Syn. Zeolite. Kirw. v. 1. 278. 

 Analcime radie. Hauy, v. 3. 182. 



Zeolite, formerly so called, is often found in trap, as if 

 passing from opaque hyalite of JCirwan (see our Tab. 57.), 

 at length leaving the spaces where it was first formed 

 empty, and giving the stone the appearance of a scoria 

 or basaltic lava. This is a red variety of basaltic trap, 

 which has hyalite of a pebble-like appearance in one part. 

 In some cavities it has partly fibrous zeolite; in others 

 the zeolite appears in fine filaments, sometimes of a silky 

 lustre, filling the holes like cotton or with loose threads, 

 which are often scattered more or less in irregular bundles, 

 somewhat radiating. The hollows which contain these are 

 mostly lined with small crystals. These at first sight look 

 like quartz, such as often sparkle in common flints, but if 

 examined with a glass their structure determines what they 

 are. See Tab. 59. and magnified figure at the middle and bot- 

 tom of this plate. 



We use the old term of zeolite, as being most familiar; 

 at present it is synonymous with analcime. 



