208 Miner a logical Notices. 



V, 



lead. With more of the assay, the odor of arsenic is sometimes 

 given off. With salt of phosphorus and borax, gives the reaction 

 of vanadic acid. Soda yields a white enamel containing grains 

 of lead- 

 According to the examinations, the mineral consists of 



« * t 



1. Dull red Tariety, 47*164 52*915 = 100-0'?9 



2. " « 46101 53-717 = 99-818 



3. Yellowish " 4927 50-57 = 9984 



The jSrst two analyses afford the oxygen ratio for the base and 



acids 1 : 3, equivalent to the formula Pb V= vanadic acid 45-335 

 lead 54-67. 



Octahedral oxyd of Antimony . — M H. de Senabmont describes 

 (Ann. Ch. Phys. [3], xxxi, 504,) an oxyd of antimony of oc- 

 tahedral forms from Seusa, near the sources of Ain-el-Bebbouch, 

 (Province of Constantine.) At one locality, the oxyd is in masses 

 often cavernous, composed of capillary filaments parallel or a 

 little divergent, and pearly or adamantine in lustre ; it is the pris- 

 matic species. But at another mine called Mimine^ the same 



oxyd exists in saccharoid masses, granular or compact, having 



cavities covered with octahedral crystals that are sometimes more 

 than a centimetre in diameter. Several admitted of measure- 

 ment and proved to be the regular octahedron, the cleavage octa- 

 hedral, but a little difficult The composition is that of the pure 

 oxyd, or oxygen 15"68, antimony 84-32. G. = 5"22-5-3, while 

 that of the prismatic oxyd is 5 56. Hardness less than that of 

 calcite. Colorless; transparent; strongly refracting without regu- 

 lar action on polarized light- Specific gravity of the massive 

 variety 5-23, and color mostly grayish; contains sometimes less 



than 1 per cent, of lead, and there may be 1 to 3 per cent, of gray 

 clay. It is probable, from the existence of thermal waters in the 

 soil below, that these crystals were formed in the humid way. 

 Oxyd of antimony is then difnorphous. Arsenous acid presents 



f 





Dechenite, a vanadate of Lead; Dr. C. Bergemann, (Pogg. Ann. 

 Ixxx, 393.) — Dechenite comes from the Lauter valley in Rhenish 

 Bavaria, near Nieder-Schlettenbach, where the rock is the '^hunter 

 sandstein.'' It occurs in small botryoidal masses, having a crys- 

 talline texture, and presenting when purest a dull red color- 

 There appear to be indications of a rhombohedral cleavage. In 

 these masses there are occasional wart-shaped grains of a more ' ^ 

 yellow color. The streak is always yellowish. Lustre of fresh 

 fracture greasy; G.=:^5 81:. H. = 4, or that of green lead ore. 

 B.B. alone in the platinum forceps it fuses easily to a yellowish 

 glass; in a glass tube gives no water; on charcoal, does not de- 

 crepitate like the known vanadate ore, but fuses easily to a yel- 



lowish green pearl, which yields a slag containing some grains of 



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