362 



DESCRIPTIVE MINERALOGY. 



pletely invests large spinelles, and sometimes with such regularity that it might be mistaken 

 for a real octahedron of clintonite. 



This mineral was discovered about fifteen years since, and named Clintonite, by Messrs. 

 J. Finch and Mather and Dr. Horton. I soon afterwards examined it, and satisfied myself 

 that it was a distinct species, although I did not go through a complete analysis. It was 

 subsequently analyzed by Mr. Clemson as above stated, and named by him Seybertite. Still 

 more recently. Dr. Thomson examined the mineral, and arriving at the same conclusion in 

 regard to its being a distinct species, gave it the name of Holmesite, in compliment to Dr. 

 A. F. Holmes of Montreal. Mohs describes it in the body of his work, under the trivial 

 name of Clintonite ; and in his appendix, introduces Seybertite as if distinct. The name 

 Clintonite was given to it by the discoverers in honor of De Witt Chnton ; and as all the sub- 

 sequent examinations have proved their opinion that it was a distinct species, to have been 



Fig. 376. 



correct, it seems to be proper that this 

 name should be retained. It has been ge- 

 nerally adopted by the German mineralo- 

 gists, and those of New- York certainly will 

 not hesitate to follow the example. 



Figs. 375 and 376 represent the second- 

 ary crystalline forms observed by Dr. Hor- 

 ton. The measurements have not been 

 ascertained. 



ANDALUSITE. 



[From its having been first found in Andalusia in Spain.] 



Made. Haay and Ckaveland. — Andalusite. Shepard. — Andalusite and Chiastolite. PAUlips. — Andalusite, or 

 Disilicate of Alumina. Thomson. — Andalousite. Beudant. — Prismatic Andalusite. Jameson. — Prismati- 

 Bcher Andalusit. Mohs. 



Fig.srr. Description. Colour red and grey. Streak white. It occurs 



regularly crystallized, and massive. Primary form a right rhombic 

 prism. Fig. 377. M on M' 91° 20'. Cleavage parallel with M on 

 M', distinct. Fracture uneven. Lustre vitreous. Feebly translu- 

 cent. Hardness 7.5. Specific gravity 3 . 104. Before the blowpipe, 

 it is infusible alone ; with borax, it fuses with great difiSculty, and only 

 when reduced to powder, into a transparent colourless glass. It is not 

 acted on by acids. 

 The species formerly known under the name of Made or Chiastolite, is now thought to be 



a mixed mineral, consisting of andalusite and the materials of clay slate, which assumes a 



variety of compound forms. 



