OKDER II. miSMATIC AXTlMONY-liAKYTE. 151 



v. Pentomous Lead-barytc. 



A new ore of lead. BERZELIUS. Ami. of Phil. XL.IV. 

 p. 154. Edin. Journ. of Science, VoL I. p. 379. 



Prismatic. Cleavage highly perfect and easily obtained, 

 parallel to a four-sided prism of 102 27', and traces in the 

 direction of its short diagonal. Traces of cleavage appa- 

 rently parallel to a horizontal prism, having its axis paral- 

 lel to the long diagonal of the vertical prism, HAIDINGER. 

 Fracture imperfect conchoidal, uneven. Colour yellowish- 

 white, straw-yellow, rose-red, pale. Lustre adamantine, 

 particularly upon the cross-fracture, inclining to pearly 

 upon faces of cleavage. Translucent. Rather brittle. 

 Hardness = 2-5 ... 3-0. Sp. Gr. = 7*77, HAIDINGER. 



It consists, according to BERZELIUS, of oxide of lead 90-13, 

 muriatic acid 6-84, carbonic acid 1 -03, water 0-54, and silica 

 1-46. The carbonic acid in this and the preceding species 

 are supposed by BERZELIUS to be accidental. He considers 

 the present species as a compound of two atoms of oxide 

 and one atom of chloride of lead, in the proportion of 38-28 

 to 61.72, while the preceding one contains one atom of each, 

 and the ordinary artificial submuriate, one atom of chloride 

 and three atoms of oxide of lead. It decrepitates slight- 

 ly before the blow-pipe, and is easily melted ; the globule 

 is of a deeper yellow than the mineral. On charcoal it is 

 reduced, and emits fumes of muriatic acid. Treated with 

 peroxide of copper and salt of phosphorus, the flame as- 

 sumes an intense blue colour. It has been found near 

 Churchhill, in the Mendip hills in Somersetshire, in ra- 

 diated masses engaged in Manganese-ores, and accompanied 

 by several other Lead-barytes and rhombohedral Lime-ha- 

 loide. 



GENUS IV. ANTIMONY-BARYTE. 

 1. PRISMATIC ANTIMOXY-BARYTE. 

 Prismatic White Antimony. JAM. Syst. Vol. II. p. 205. 



