Descriptive Catalogue of Rocks and Minerals. 251 



y\RT. IX. — Descriptive Catalogue of Rocks and Minerals 

 collected in JV. Carolina^ and forwarded to the American 

 Geological Society, by Denison Olmsted, M. -4.G.S. Pro- 

 fessor of Chemistry, <^n\ in the College of jV. Carolina, 

 April, i822. 



No. 1. Sulphate of Barytes, exhibiting the foliate struc- 

 ture and glistening lustre of the mineral, (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 mass, as in No. 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- 

 rytes, in cubical and nodular pieces from three to six inches 

 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 regular prisms. 

 Masses of the Barytes of equal purity with No. 2, and six 

 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 were 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 red, displayed at a 

 certain angle, will be particularly observed. 



