TAB XX 



CALX carbonata primitiva, var. 



Primitive Carbonate of Lime, var. 



Class 2. Earth. Ord. 1. Homogeneous. 

 Gen. 1. Lime. Spec. 2. Carbonate of lime. 



Var. Crystal primitive, with secondary faces parallel to both those 

 of the equiaxed and metastatic. 



This curious crystal is sometimes found at Castle-Town in 

 Derbyshire. Its gangue is generally a bituminous limestone. 

 It is a little milky on the outside, and roughish ; those edges 

 excepted which are rounded : see the left-hand figure. The 

 right-hand figure has broad faces leading to the equiaxed 

 crystal, which faces are as it were polished, and in the mid- 

 dle is a longitudinal line showing the edge of the nucleus, 

 consequently the laminae of superposition : see the upper 

 part of the right-hand figure. There are also rough faces 

 leading towards the metastatic crystal : see the lower part 

 of the right-hand figure. As I had but indifferent specimens 

 myself, I borrowed the specimen here figured of Mr. Richard 

 Phillips, thinking it well worth noticing. The little black 

 spots are drops of mineral pitch, which mostly accompany 

 these varieties. They have generally been termed primitive 

 crystals, without further consideration. In an arranged col- 

 lection they may be placed near to the primitive. 



