[ 242 ] 

 XXXIII. Mineralogical Notices. 



CARMINE SPAR. BY F. SANDBERGER. 

 [Poggendorff's Annalen, vol. Ixxx. p. 391.] 



THIS mineral accompanies Beudantite at Horhaiisen; it 

 occurs in tufts of slender needles, or in spherical masses 

 with a radiated structm-e ; its ciystalline form could not be de- 

 termined. Colom* carmine-red, passing into brick-red; it is 

 highly translucent, with a \dtreous lustre inclining to pearly. 

 It is brittle, and appears to possess cleavages parallel with the 

 faces of a rhombic prism. Hardness between calcareous spar 

 and rock salt. Heated in a closed tube it experiences no altera- 

 tion. Before the blowpipe it fuses readily upon charcoal into a 

 gray scoria, diffusing copious arsenical fumes ; with soda, glo- 

 bules of lead are obtained ; and vnXh borax, a strong reaction of 

 oxide of ii'on. It dissolves readily in hydrochloric and nitric 

 acids. 



The author was not able to obtain a quantity sufficient for a 

 quantitative analysis; but his experiments appear to him to 

 prove satisfactorily that the mineral is composed of the anhy- 

 drous arseniates of lead and iron. 



DECHENITE. BY DR. C. BERGEMANN. 

 [Poggendorff's Annalen, vol, Ixxx. p. 393.] 



This mineral was discovered by Dr. Krantz in veins of a lead 

 ore containing galena, carbonate and phosphate of lead, at Lau- 

 terthal in Ehenish Bavaria. It occm-s in kidney-shaped ciystal- 

 line aggregations, or in smaU thin and cm-ved plates. It was 

 impossible to detemiine its ciystalline form ; there are, however, 

 indications of cleavages which appear to belong to a rhombohe- 

 dron. Its colom- is dark red, passing sometimes into yellow ; 

 in powder it is always yellow. It is translucent, and has a fatty 

 lustre; spec. grav. 5 81; hardness scarcely 4, equal to that of 

 phosphate of lead. Before the blowpipe it fuses readily into a 

 yellowish glass without decrepitation. It was found, on analy- 

 sing the purest specimens, to consist solely of oxide of lead and 

 vanadic acid in proportions con-espouding to the simple formula 

 PbO, VO^. The complete absence of chloride of lead distin- 

 guishes it from all the compounds of vanadium and lead hitherto 

 analysed. 



The analysis was made by dissolving the mineral in dilute 

 nitric acid, which is easily effected, separating the lead by long 

 digestion with sulphuric acid and subsequent addition of alcohol. 

 The sulphate of lead proved perfectly free from vanadic acid. 

 The 8ulphui"ic solution of the latter constituent was evaporated 



