40S Yeates and Ay res — Occurrence of Plattnerite 



the hardness at about 5, and the specific gravity at 8"54; and 

 its composition, PbO, 92-66; O in excess of PbO, 6 -20 (by 

 direct determination.) In another paper before the same 

 society on March 12th, 1889, Prof. Heddle* describes a speci- 

 men of plattnerite from Belton Grain Vein, Wanlockhead, 

 Scotland, and a specimen from Leadhills, both of which had 

 been in his possession some years. The specific gravity of the 

 first-is given at 8*8 to 8 - 96 ; and that of the latter, at 9*27. In 

 May, 1889, the writer of this paper identified as plattnerite a 

 specimen, which had been sent to the National Museum, by 

 Mr. Waldo J. Clark, of Mullan, Idaho. A brief preliminary 

 note, announcing the occurrence, was sent to this Journal. A 

 reference to this note appeared in the July number, f as did, 

 also, a note on the same subject from Prof. H. A. Wheeler, of 

 St. Louis, giving a brief description and an analysis. In the 

 August number of the Journal, Messrs. J. D. and E. N. 

 Hawkins:}: described a specimen of the plattnerite, which had 

 fallen into their hands, giving two analyses. 



In the meantime, the writer had secured a considerable 

 quantity of the material, with the view to describing, more in 

 detail, its occurrence in Idaho; and his investigations had 

 developed facts not referred to by Mr. Wheeler or the Messrs. 

 Hawkins. 



In a letter from Mr. Clark, who had kindly furnished the 

 writer with the material, he says that he discovered the platt- 

 nerite in a tunnel in the "You Like" lode, Hunter mining 

 district, three miles northwest of Mullan, Idaho, on a spur of 

 the Coeur d'Alene mountains, at a distance of 70 feet from the 

 surface ; and that it occurred in " round knobs or bunches " in 

 a continuous line, touching each other " for a distance of 20 

 feet, when the iron§ appeared to crowd it nearly out for 10 feet, 

 then considerable of it for 10 to 15 feet farther, when it dis- 

 appeared," and no more was found as far as the tunnel was 

 run, a distance of 40 feet. 



The intimate associates of the plattnerite are limonite and 

 white pyromorphite, the former occurring in botryoidal masses 

 and as a brown ocher; the latter, in crystals, rarely in veins, 

 scattered through some of the nodules. The plattnerite occurs 

 in botryoidal nodules embedded in a mixed ocher of limonite 

 and plattnerite, which contains, scattered through it, loose crys- 

 tals of pyromorphite, when the nodule, within, contains them. 

 When this ocher is cleaned off, and the nodule is broken open, 

 the fresh surface exhibits a small conchoidal fracture and a 

 bright metallic-adamantine luster, which tarnishes and becomes 



*Min. Mag., London, vol. viii, p. 203 (1889). 



f This Journal, xxxviii, July, 1889. p. 79. 



\ This Journal, xxxviii, Aug. 1889, p. 165. § Limonite. 



