396 VANADIATE OF LEAD. 



implanted globules or incrustations. Colour 

 varying from straw - yellow to reddish- 

 brown. Opaque. Dull. Lustre of fractured 

 surface resinous. Streak white or yellowish. 

 Brittle. Fracture uneven or flat-conchoidal. 

 H. 2-75 to 3. S.G. 6-6G to 7'23. 



Fig. 448. 



Fig. 449. 



Covin. Vanadiate of lead, or SPb^ V + 

 Pb CI = vanadiate of lead 89-72, chloride of 

 lead 9-78 = 100. 



Anahjsis, from Wanlock Head, by R. D, 

 Thomson : 



Vanadic acid . . . 23-44 

 Oxide of lead . . . 66-33 



Lead 7-06 



Muriatic acid . . . 2-45 



99-28 



BB decrepitates strongly, and on char- 

 coal fuses to a globule which yields metallic 

 lead, with emission of sparks and the for- 

 mation of a yellow film on the charcoal. 



Dissolves easily in nitric acid, and nitrate 

 of silver throws down a large quantity of 

 chloride of silver from the solution. 



The ore from Wanlock Head fuses readily 

 on charcoal, exhaling odours of arsenic, 

 yields globules of lead, and after fusion for 

 some time in the inner flame, likewise yields 

 a steel-grey, very fusible slag, which ex- 

 hibits the reaction of chromium. With 

 muriatic or sulphuric acid forms a green 

 solution, with separation of chloride or sul- 

 phate of lead. 



Localities. — Scotch. Wanlock Head, Dum- 

 friesshire, on common and cupreous Ca- 

 lamine, at the Hegh-pirn of the Susan- 

 nah Mine. — Foreign. Beresowsk, near 

 Katherinenburg, in Siberia, associated with 

 phosphate of lead. Zimapan, in Mexico. 

 The Zanchen, in S.E. Carinthia. 



Name. The name Vanadinite is derived 

 from Vanaclis, a cognomen of the Scandi- 

 navian goddess Freia. 



The following will be found a ready test 

 for this mineral. If nitric acid be dropped 

 on the crystals, they become first deep red, 

 owing to "the separation of the vanadic acid, 

 and afterwards (upon its solution) of a 

 brilliant yellow. {Reddle.) 



VARIOLITE. 



31. P. G. Principal Floor, Wall-cases 

 13 and 45 (British.) 



Vakiegated Copper-oke, Jameson. See 

 Erubescite. 



Variegated Vitreous Copper, Phil- 

 lips. A mixture of Vitreous Copper (Copper- 

 Glance) and Copper Pyrites, found in most 

 of the Cornish mines in which the former 

 ore occurs. The colour is that of tempered 

 steel, violet-blue, greenish and yellow. 



Variolite. a dark green variety of 

 Felspar, containing disseminated spherules 

 or globular particles of a paler colour. 



Variolite is an orbicular rock, generally 

 of a deep green colour, speckled with dif- 

 ferent tints of grey. It takes a high polish 

 (especially in those parts which are spotted) 

 the brilliancy of which equals that of the 

 finest oriental stones. The most remarkable 

 circumstance attending this stone (whence 

 probably it derives its name) is, that in 

 weathered specimens the spots, which con- 

 sist of a black point surrounded by a brown, 

 ring, stand out from the surface of the stone, 

 showing that the influences which had pro- 

 duced the erosion of the base of the rock, 

 had not been able to produce an equal effect 

 on the harder portions of it. 



Though most frequently of a dark green 

 there are white, blue and red varieties, with 

 others of intermediate tints. The spherules 

 vary also in colour. In some the black 

 points are surrounded with a white ring, 

 while in others they have, in addition, a 

 second whitish circle, which gives it exactly 

 the appearance of a small Onyx. These 

 singularities, coupled with the remarkable 

 appearance of the stone, caused it to be 

 believed by the vulgar, in times of greater 

 ignorance than the present, to be an effec- 

 tual remedy for small-pox,whence the name 

 perhaps (from variola, small-pox, and xifo?, 

 stone). 



Anciently this stone was brought from 

 the Indies, but it has since been discovered 

 in various countries of Europe, especially in 

 France (in the river Drac), Piedmont, and 

 Switzerland. It is also found at Durance, 

 in Savoy, where the spherules, which are 

 white or greenish- white, are often changed 

 into Kaolin or China-clay; and Antrim co., 

 in Ireland. 



Large masses are also procured from the 

 High Alps. It is used to ornament cabinets, 

 and for caskets, snuff-boxes, &c. 



Analysis, bv Belesse, of the rock. (S.G. 

 2-896 to 2-934): 



Silica 52-79 



Alumina .... 11-16 



