Mineralogy. 361 



present Ober-Berghauptmann, or director of every thing connected with 

 mining proceedings in Saxony. It is in compliment to that nobleman, 

 that I propose the name of Herderite for the species. 



2. Herderite occurs imbedded in fluor, in the tin mines of Ehrenfried- 

 ersdorf, in Saxony. It resembles apatite, with which it was formerly con- 

 founded, in a remarkable degree; particularly some of those named aspa- 

 ragus-stone : such as the variety from Zillerthal, in Salzburg, and that 

 from Hof in Gastein in the same country, which is found accompanying 

 the axotomous iron-ore of Mohs, and still more so certain pale greenish- 

 white masses of the same species, which occur, though in small quantity, 

 along with the zoisite from the Saualpe in Carinthia. The resemblance 

 among those species is sufficient to class the Herderite in the genus Fluor- 

 haloide of Mohs, in which it may be henceforth included as the M pris- 

 matic Fluor-haloide." — Ann. of Phil. July 1828, p. 1. 



22. Fahlunite. — Count Trolle-Wachtmeister, (Kongl. Vttensk. Acad. 

 Handl.for 182'%) has given the results of an examination of three varieties 

 of this mineral. 



The first variety is uncrystallized, has a black colour, a brown streak, a 

 spec. gr. = 2.68. The second variety is crystallized, in forms like the to- 

 paz, has a gray colour, a white streak, and a spec. gr. = 2.74. The third 

 variety blackish gray in colour, white in streak, and the spec. gr. = 2.79. 

 The general formula of this combination of isomorphous bodies is = MS 2 

 + 3 AS 4- 2 Aq. All these varieties are found in the Fahlun Mine. 



23. Diallage.—Dr Kdhler of Cassel (Poggendorff 's Annalen der Physik 

 und Chemie, vol. xii. p. 101, &c.)has examined several varieties of diallage, 

 and infers from this examination, that metalloidal diallage, bronzite, and 

 hypersthene, are subspecies of the pyroxene, (paratomous augite spar) and 

 not like the Schiller spar and antophyllite species of the Schiller spar family. 



1. Metalloidal Diallage from the Baste, near Harzburg, on the Harz. — 

 This mineral forms a constituent of the great granular gabbro or eupho- 

 tide, and has a highly perfect cleavage parallel to one direction. The lustre 

 is pearly and metallic, the colour olive and leek-green, brown, and gray ; 

 the hardness = 3.75 . • . 4.0, the spec. gr. = 3.22 . . . 3.23. Like the sma- 



