ORDER II. MACROTYPOUSPARACHROSE-BARYTE. 107 



Massive : composition granular, sometimes small 

 and even impalpable, sometimes it is columnar. 



OBSERVATIONS. 



1. The varieties of the present species have often been 

 confounded with other minerals, one of which, too imper- 

 fectly known to be yet received in the system, is enume- 

 rated in the Appendix. Though these species will not 

 in future be confounded if we attend to their charac- 

 ters, yet they bear to each other a strong degree of re- 

 semblance, which extends likewise to some of the follow- 

 ing species. The genus Parachrose-baryte joins to that of 

 Lime-haloide, and explains, by the great similarity of the 

 species contained in both these genera, the differences in 

 the opinions which have prevailed among mineralogists in 

 spite of the marked distinction among their characteristic, 

 properties. 



2. A variety of the present species has been found by 

 Du ME NIL to consist of 



Oxide of Manganese 54-60. 



Carbonic Acid 3375. 



Oxide of Iron 1-87- 



Silica 4-37. 



Lime 2-50. 



In its pure state it is represented by Mn C 2 , which ex- 

 presses 62-35 oxide of manganese, and 37-65 carbonic 

 acid. It effervesces rather briskly in nitric acid ; before 

 the blow-pipe its colour is changed into grey, brown, and 

 black, and it decrepitates strongly, but is infusible without 

 addition. It is easily soluble in glass of borax, which be- 

 comes violet-blue. If exposed to the air, its natural colour 

 is changed into brown. Many bright rose-red varieties 

 become paler on being exposed in a similar manner. 



3. The varieties of the present species occur generally 

 in metalliferous veins, with various ores of silver and lead, 

 also with Copper-pyrites and Iron-pyrites, rhombohedral 

 Quartz, &c. They have likewise been found in beds in 



