TAB. XXXIII. 



CALX carbonata, var. metastatica. 

 Carbonate of Lime, var. metastatic. 



Class 2. Earths. Order 1 . Homogeneous. 

 Gen. 1. Lime. Spec. 1. Carbonate of Lime. 



Blv. 1. Crystallized. Var. Metastatic. 

 Syn. Dent de cochon. De Lisle, tab. 1. p. 530. 



2 



Chaux carbonatee metastatique. D Hauy, v. 2. 



r 



p. 134. ' 



This form or variety of crystallization of carbonate of 

 lime is perhaps one of the most common, and has ob- 

 tained the name of Dog's tooth spar in England, and that 

 of Dent de cochon, or Swine's tooth, in France. This 

 crystallization is prevalent of different sizes, colours, &c, 

 in Derbyshire, some affording good examples of the pri- 

 mitive rhomb, being clear, and differing very Tittle from the 

 true Iceland, crystal, which is reckoned the most pellucid, 

 and for a figure of which see our tab. 2. The left hand 

 lower figure shows the usual construction, the edges of the 

 opposite pyramids meeting on the edges of the primitive 

 rhomb, when the obtuse ends are opposite to each apex *, 

 the more acute angles forming three principal ones, and the 

 obtuse three less distinct ones : thus each pyramid has six 

 sides, the acute and obtuse meeting in alternate order at the 



* The metastatic is formed by an addition of lamina?, formed of rhom- 

 boidal molecules upon the faces of the primitive rhomb, each plate decreasing 

 in width twice its thickness. This will be more fully explained hereafter. 



