40 Dr. JR. D. Thomson on the History [Jan. 



ternally, or glimmering and resinous ; fracture, flat, con- 

 choidal or uneven; opaque, soft, streak sisken-green. He 

 conjectured that it was similar to the Zimapan mineral, and 

 there can be no hesitation in admitting that his suspicions 

 were correct.* 



Native vanadiate of lead has been recently obtained at 

 Beresow, near Katharinenburg in the Uralian Mountains, 

 and its mineralogical characters have been investigated by 

 Gustav Rose.f Among the lead ores in the gold mines, a 

 green ore of lead is found, which crystallizes in double six 

 sided prisms. It melts before the blow-pipe, crystallizing 

 on cooling, and contains some phosphoric but no arsenic 

 acid. In a specimen brought from Eeresow, Rose observed 

 the six-sided prisms on one side green, and on the other 

 brown. Having tried them before the blow-pipe, he found 

 the brown crystals to be vanadiate of lead. They are re- 

 gular six-sided prisms, some of them very small, others 

 larger. The crystals of greater size are found near the lead 

 ore, and contain a nucleus of the ore. The crystals possess 

 a chesnut-brown colour, a shining lustre, especially the 

 small ones, and have the same hardness as the grey lead 

 ore. Before the blow-pipe the mineral decrepitates strongly, 

 melts upon charcoal into a globule, and the lead is reduced. 



With salt of phosphorus it fuses in the outer flame into 

 a glass, which when hot is reddish yellow, when cold yel- 

 lowish green ; and in the inner, into a glass possessing a 

 chrome green colour. 



In nitric acid it dissolves readily. The solution gives with 

 nitrate of silver, a considerable precipitate of chloride of 

 silver. The filtered solution gives with sulphuric acid, a 

 white precipitate of sulphate of lead, and then precipitated 

 by suphuretted hydrogen, a brownish red precipitate of 

 sulphuret of vanadium. Rose concludes from these cha- 

 racters that the mineral he examined was identical with 

 the brown lead mineral from Zimapan. The vanadiate of 

 lead of Beresow is found in crevices in granite, .which 

 communicate with the quartz veins in which gold is found. 



The mineral is liable to be confounded with the lead ore, 

 because both substances crystallize in six-sided prisms, and 



* Journal de phys. Ixiii. 38. Jameson's Mineralogy, iii. 413. 

 t Poggendorff Annalen der Chemie, xxix. 455. 



