Notices of some Minerals. 333 



the Royal Dublin Society, has enabled me to ascertain that I 

 have confounded together, in my mineralogy, (vol. i. p. 244.) 

 two distinct species of minerals under the name of nacrite. 

 For the sake of distinguishing these two species from each 

 other, I restrict the name nacrite and apply it only to a 

 mineral from America, which I analysed and described in 

 the year 1827. To the other mineral from Ireland, I shall 

 apply the name talcite ; as it was probably to it that this 

 name was given by Kirwan. — See his Mineralogy, vol. i. 

 p. 149. 



Nacrite. — The only specimen of this mineral which I 

 have seen, I received about ten years ago from Dr. Torrey 

 of New York. It was labelled Green mica in mica slate from 

 Brunswick, Maine. The specimen consisted of light green 

 coloured scales scattered unequally through a rock com- 

 posed chiefly of quartz with abundance of iron pyrites 

 interspersed. 



The colour of the scales is white with a beautiful shade 

 of light emerald green. 



Lustre splendent and pearly. 

 Composed of plates which are flexible ; but not elastic. 

 When viewed under a microscope they have some thickness. 



They have one very distinct cleavage parallel to the 

 broad faces of the scales. They shew some obscure in- 

 dications of two other cleavages, which would indicate an 

 oblique four-sided prism as the primary form of their 

 crystals. 



Translucent. — Feel not unctuous. 



Very soft. — Specific gravity 2*788. 



After ignition they still retain their pearly lustre, but 

 have lost their green colour and become silvery white. 



Fuses with difficulty before the blow-pipe. Its con- 

 stituents are as follow : 



98-712* 99-58f 

 * By my analysis. 



t Yellow earthy talc from Merowitz, analysed by John. — Jour, des Mines, 

 xxiii. 384. 



