140 



that it was produced from Madrepores ; but it discovers no 

 certain characters of a primitive organic formation : be- 

 sides, it has so great a resemblance to the real Madrepores, 

 that it has thence borrowed its name. It is of a gray co- 

 lour, composed of divergent prisms, brilliant on their trans- 

 verse fracture, and of a black and duller colour on the 

 longitudinal fracture. The fracture exhibits a tissue of 

 small bent laminae ; it is entirely opaque, brittle, rough to 

 the touch, and of moderate hardness ; the intervals be- 

 tween the bundles which compose it are in part filled with 

 small white leaves of Calcareous Spar." 



There are three or four analyses of this substance. Ac- 

 cording to Molle, a hundred grains of it contain, 



Lime 63 tV 



Alumine 30 -fa 



Iron 10 44 



1 5 



Analysed by Klaproth, it was found to contain, 



Carbonate of Lime 93 00 



Magnesia 50 



Iron 1 25 



Charcoal 50 



Sandy Silex 4 50 



An atom of Oxide of Manganese 



99 75 



Hauy's experience gave him reason to think himself 

 satisfied that this substance, which has been made so con- 

 spicuous, is a Carbonate of Lime; and my specimen is a 

 confirmation of this opinion, being certainly nearly the 

 same thing ; but now the improved knowledge in crystal- 

 lography helps us more readily to decide it. Like the Madre- 

 porite, at first sight it looks like Basalt, and somewhat re- 



