129 



TAB. CCCLXIX. 



CALX carbonata. 

 Carbonate of Lime. 



Div. 1. Crystallized. 



Carbonate of Lime is so abundant in varieties and mo- 

 difications of its crystals, that we shall select only such 

 specimens as show something peculiar or instructive. In 

 the present instance we exhibit it with longer prisms than 

 usual, which help to give it the aspect of Quartz, which is 

 so common with a longish prism. Some specimens, but 

 such are somewhat rare, are not far inferior in lustre and 

 transparency to Quartz, but, like Diamonds and other dia- 

 phanous brilliant subjects, would be best understood by 

 comparison. Perhaps the brightest Carbonate of Lime 

 would be, in comparison to Quartz, as cut Paste is to Dia- 

 monds ; so that even the most experienced must try the 

 coldness or hardness, to help his judgement. The first 

 method would not hurt the Paste or Carbonate of Lime, 

 but the latter would damage them ; and specimens have 

 now and then been hurt by trial. We have, however, the 

 form of the pyramid to judge by; for Carbonate of Lime 

 never has been found with the obtuse equiangular six-sided 

 pyramid of Quartz, or representing any of the numerous 

 varieties of it : — thus the structure points out a distinction 

 which, when understood, is discerned in an instant. The 



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