J\'^atfalPs Geological and Mineralogical Remarks. '24'5 



pseudo productions of the Missouri, have yet, however, 

 been discovered in the territories of the United States. 



The coNDRODiTE, orBRuciTE, aloiost peculiar to Spar- 

 ta, discovered Hkewise by the celebrated Berzelius, in Fin- 

 land, accompanied by gray Spinelle, is (according to an un- 

 published analysis which I made in 1820,) a "silicate of 

 maj];nesia with an accidental ^ovWoxx of fluoric acid and 

 iron. The same result has been obtained by Dr. Torrey, 

 from whom I copy the following description of its crystal- 

 lization. It occurs occasionally in small four-sided prisms, 

 (of a paler colour than the amorphous masses,) with rhom- 

 bic bases of 124° and 56° truncated on the acute lateral 

 edges by planes which form with the contiguous sides of 

 the prism angles of 122° and 114° The prism is termina- 

 ted by dihedral summits whose faces meet under an obtuse 

 angle, and correspond to the acute, truncated edges of the 

 prism. The edges of the summits are oblique to the axis 

 of the prism, but not parallel to each other ; or they may 

 be said to be atternaieiy oblique at each extremity." 



Haiiy, also, by cleavage, had obtained from it a rhom- 

 boidal prism ; andBerzelius. who then compared it analyti- 

 cally with his condrodite, concluded it to be identic. The 

 former, with his usual sagacity, referred it to his peridot; 

 as it does not indeed very materially differ in composition 

 from ohvin or amorphous chrysolite: still the crystalliza- 

 tion proves it to be a very distinct species. It is of a 

 bright brownish yellow, bordering on orange, disseminated 

 in masses commonly about the size of a hazle nut, exhibit- 

 ing more or less of the rhombic form, throughout a white 

 and fohated lime-stone, generally containing scattered 

 hexagonal laminae of plumbago, and more rarely, bluish 

 pellucid crystals of phosphate of lime. It is imperfectly 

 lamellar in one direction, splintery in the other, with a glas- 

 sy or almost resinous lustre, the fragments either translu- 

 cent or nearly opaque, and sufficiently hard to scratch glass. 

 Before the blowpipe it is infusible, but with borax forms a 

 glass, though not very readily. Its gravity is a small frac- 

 tion above 3. 



Throughout the valley of Sparta the condrodite is by no 

 means uncommon, but variable in its appearance. The 

 finest and clearest masses are obtained at the town of Spar- 

 ta. Though abundant at Franklin, it is here opaque and 

 of a deeper tinge of colour. It occurs thickly dissemina- 



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