PHYSIOGBAPHY. CLASS II. 



OBSERVATIONS. 



1. It cannot excite our surprise to see the varieties of a 

 species, which are so numerous as in prismatic Hal-baryte, 

 particularly in regard to composition, variously divided in 

 the mineralogical systems into sub-species and kinds, not- 

 withstanding the close connexion of all these varieties by 

 immediate transitions. First the friable varieties were se- 

 parated from the rest under the denomination of Earthy 

 Heavy-Spar. Among the crystallised ones, those of a tabular 

 appearance, or such as have the face ?r + co predominant, 

 also the massive varieties, consisting of straight lamellar 

 particles of composition, have been called Straight lamellar 

 Heavy-Spar, while Granular and Compact Heavy-Spar ap- 

 plied to such massive varieties as consist of granular or 

 impalpable particles of composition. Prismatic Heavy-Spar 

 refers to crystals in which the faces of either vertical or 

 horizontal four-sided prisms form the most prominent 

 feature, and which prisms are sometimes aggregated 

 in massive varieties, consisting of longish granular par- 

 ticles of composition ; columnar Heavy-Spar to very thin 

 crystals that are aggregated longitudinally. Implant- 

 ed globular or reniform shapes, also massive varieties, 

 shewing the curved lamellar composition, are comprehend- 

 ed under the denomination of the Curved lamellar Heavy- 

 Spar, sometimes called Fibrous, if the composition be very 

 delicate. Radiated Heavy-Spar or Bolognese-Spar is a par- 

 ticular denomination of a variety of this species in imbed- 

 ded globules, consisting of columnar particles, generally a 

 little broad and radiating from the centre. Some mine- 

 ralogists have moreover distinguished Hepatite (Baryte sul- 

 fatee fetide. HAUY), or those varieties which develope a 

 hepatic odour, on being broken or rubbed with hard bo- 

 dies. Some varieties at last were separated from the rest 

 on account of their being more or less decomposed, and 

 designated by the addition of that word. 



All these distinctions are founded upon characters which 

 are not essential. It is rendered probable, however, by se- 

 veral observations, that the species of prismatic Hal-ba- 



