tiO Chemical Examination of American Minerals. 



of Cieaveland's Mineralogy, the first part of which was print- 

 ed before Mr. Se^bert read his paper in Philadelj hia. Indetd 

 the fluoric acid is detected with the greatest ease in the variety 

 of Brucite, which is so abundant at Sparta. Sulphuric acid 

 immediate!}' decomposes the mineral, while fumes are libera- 

 ted which distinctly corrode glass. 



The chondrodite of D'Ohsson, which has already received 

 so many appellations, lias recently been found identical with 

 the Humite of Count Bournon, a mineral which occurs among 

 the products of Vesuvius. As early as the year 1823, Mr. 

 Nutlall communicated to me his opinion, that the Humite 

 was not a distinct mineral from the Brucite. At his request, 

 Mr. Bowen, now Professor of Chemistry in the University of 

 Nashville, submitted to experiment the granular variety of 

 the Humite, which accompanies the idocrase of Vesuvius, 

 and detected in it fluoric acid.* A full account of this mine- 

 ral, under the name of chondrodite, is given in the *' Pro- 

 dromu delta Mineralogia Vesuviana, par T. MonticeUi et 

 N. Covclli, Napoli, 1825." The Brucite and Humite are 

 quoted as synonyms. Its primitive form is exactly that of 

 the chondrodite, as given by Hai.y, Traite de Min. ii. 

 p. 476-7, second edition. f Two secondary forms are de- 

 scribed, one of which had been already noticed by Haiiy. 

 They are represented in Tab. III. f. 41 and 42. The first 

 is a rectangular prism, terminated by two quadrangular pyra- 

 mids ; the second is a new variety, termed octovig; simal, or 



'" See a note to Mr. Nutlall's memoir, in Silliman's Journal, V. p. 240. 



•[ The primitive form of Brucite, given by Mr. Nuttall and Prof. Cleave- 

 land from my notes, is incorrect. I mistook for that mineral, some small 

 crystals of amphibole, which are generally associated with the Brucite. 

 The Brucite itself is scarcely ever seen crystalized in the United States. 

 Occasionally it exhibits the form of short rhombic prisms, differently modi- 

 ned, but so imperfect that their precise shape cannot be determined. 



