TAB. LVII. 



SILEX Analcimus, var. compactus. 

 Compact Analcime. 



Class 2. Earths. Order 1. Homogeneous, 

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



Div. 3. Amorphous. 



Syn. Analcime. Haiiy, v. 3. 1 80. 



I his curious substance is not uncommon in Great Britain, 

 wherever basalt "and trap are found. We have some spe- 

 cimens from different parts of Scotland, which contain it 

 in nodules. The present specimen came from the Isle of 

 Isla. It is somewhat stalactitical, and extremely various in 

 its shapes, sometimes forming roundish drops from the size 

 of a pin's head to that of a large pea, and often of a knotty 

 elongated figure like a potatoe. It seems to be a transition 

 from quartz, and decomposes into filaments forming zeo- 

 lite. This specimen exhibits it beginning to form filaments. 

 The bottom of the larger mass, which somewhat resembles 

 the humerus, or thigh bone, of an animal, appears once 

 to have been in a thick fluid state, and might give some idea 



of the forming of the flints in chalky rocks, (see page 15.) 



K 2 



