Descriptive Catalogue of Rocks andAIhierals. 2ol 



Art. IX. — Descriplive Catalogue of Rocks and Minerals 

 collected in Jsf. Carolina^ and forwarded to the American 

 Geological Society^ by Denison Olmsted, M. A.G<S. Pro- 

 fessor of Chemistry^ ^c. in the College of X. Carolina, 



No. !• Sulphate of Baryles^ exhibiting the foUate struc- 

 ture and glistening lustre of the niineral. (handsome.) 

 ^ 2. The same, in mass, of a cubical figure, with quartz 



' on one side, (very handsome.) 



3. The same, exhibiting its lustre when so broken as 

 to present the edges of the laminae distinctly. 



These three specimens were obtained at the same place, 

 near Hillsborough, where an abundant formation of the 

 mineral has lately been discovered. It occurs associated 

 with quartz, with which, as in Nos. 1. and 2., it is frequent- 

 ly united in the same mass, the quartz adhering to its sides, 

 and shooting perfect crystals through its njass, as in iSo 1. 

 ": ~ An excavation of only four feet in depth and five or six in 



length has yet been made ; but this has disclosed the Ba- 

 il ^jt6s, in cubical and nodular pieces horn three to six inclies 

 If in diameter, lying side by side, and running into crystallized 



quartz on the right and left. The region around is strewed 

 with fragments of quartz, variously figured, and everywhere 

 shewing a strong tendency towards crystallization, and of- 

 ten actually forming congeries of very res^ular prisms. 

 Masses of the Barytes of equal purity with No. 2. aiid six 

 I inches in diameter, were taken from the lowest layer, and 



' - the size, it was said, regularly increased with the depth. 



The prevailing rocks of the vicinity are chlorite and clay 

 slates, (very handsome, delicate blue.) 



4. Mica^ from Henry Co. Virginia. The superb lustre 

 and fine shades of colour which this specimen exhibits 

 Were common to a great number of pieces brought to me 

 at the same time. 



They were furnished by a person who evidently had 

 employed very little pains or skill in selecting the specimens. 

 He reported that those of this kind vfevQ exceedingly com- 

 mon. The small piece is added to shew the splendid colours 

 exhibited by refraction from minute veins in a thin lamina- 

 An effulgence of vivid green, blue, and rei^ displayed at a 

 <^ertain angle, will be particularly observed. 



