Notices of Memoirs — Mineralogy. 175 



Dr. Genth's studies lead him to conclude — "1. That at the great 

 period when the chromiferous chrysolite beds (in part subsequently 

 altered into serpentine, etc.) were deposited, a large quantity of 

 alumina was separated, which formed beds of corundum. 2. That 

 this corundum has subsequently been acted upon, and thus been 

 changed into various minerals, such as spinel, fibrolite, cyanite, and 

 perhaps into some varieties of felspar; also into tourmaline, 

 damourite, chlorite, and margarite, 3. That a part of the products 

 of the alteration of corundum still exists in the form of large beds 

 of mica- (damourite-) and chlorite-slates or schists. 4. That another 

 part has been further altered and converted into other minerals and 

 rooks, such as pyrophyllite, paragonite, beauxite, lazulite, etc." 



F. W. E. 



II. — On a Pseudomorphous Formation after Felspar. XJeber 

 eine pseudomorphe Bildung nach Feldspath. Von Dr. Eichard 

 v. Drasche. Tschermak' s Mineralogische Mittheilungen, 1873, 

 Heft ii. pp. 125-128. 



THE pseudomorphs forming the subject of this communication 

 were obtained from a limestone-quarry near Budweis, in 

 Bohemia. This limestone incloses, among other minerals, large 

 rounded masses of a greenish substance, resembling steatite. Each 

 mass, when broken open, usually exhibits a white or greyish nucleus 

 of ellipsoidal form, sharply separated in most cases from the en- 

 veloping mineral. The following analyses exhibit the composition 

 of the nucleus (I.) and of the surrounding substance (IL). 



I. ir. 



Silica 60-49 34'63 



Alumina 24-33 17-13 



Ferrous Oxide 1-61 



Lime 4-07 



Magnesia 1-46 33'38 



Potash 4-23 



Soda 5-04 



Loss on ignition 1-69 ^.... 13-93 



101-31 100-68 



It appears from these analyses that the composition of the nucleus 

 is that of a felspar approximating to andesine ; whilst the green in- 

 vesting mineral stands near to pennine or to pseudophite, and is 

 evidently a product of the alteration of the felspar. F. W. E. 



III. — On Syngenite. Ueber den Syngenit. Von dem c. M. v. Eitter 

 V, Zepharovich. Sitzungsh. d. k. ATcad. d. Wissensch. : Math.- 

 Naturw. Classe. Ixvii., 1873, pp. 128-142. 



SYNGENITE is a new mineral species, discovered a short time since 

 in the salt-deposits of Kalusz, in Eastern Galicia. It occurs in 

 association with cubic crystals of rock-salt, and in general appearance 

 resembles gypsum, from which it differs, however, both in its hard- 

 ness and in the character of its cleavage. Chemical examination 



