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Foin^th Sujyplenieiit to Danas Mi7ieraIogy, 125 



this new discovery was made by M. J. A. Hugard, assistant in the mineralogical 

 department in the Museum d'Histoire Naturellc, Paris. Some of the crystalline 

 masses obtained by him were as large as the fist; and while black externally, they 

 are pale brownish -yellow to nearly colorless within. The crystals are peculiarly 

 fine and of interesting forms. The rock or gangue is a talcose schist of a greenish 

 color. 



Pjauzttk [p. 469, and III]. — Kenngott gives a fuller account of the piatizite of Tuf- 

 fer in the Jahrb. k. k. Geol. Reichs., 1856, p. 91. The color of this slaty coaMik« 

 resin is brownish to greenish-black; the thinnest splinters colophonite-brown by 

 transmitted hght. Streak light to amber-brown. G.^M86. 



r 



PrTCHBLESDK [p. 107]. — The coracite of LoConte is referred to pitchblende by 

 Dr. F. A, Genth. Analysis afforded (Am. J. Sci. [2], xxili, 421) : 



e tr 3Pe *1 Mg Ca th Si C and fl 



46-21 16-47 3-51 0'52 0-56 5-33 7*39 13-15 6*U=99"28 



The ratio of oxygen in UO to U20^ is very near 1 : 4. 



Plumbic Ochre [p. 109]. — Tlie Plumbic ochre occurs with native lead in Mexico 

 at the mine San Guillormo [see Lead] in granular masses of brownish-red, grayish or 

 yellowish color ; 0.^798 — 7*83. Composition according to Dr. Pugh — 



Pb 



Pe 



C 



Si 



S and loss 



9291 



5-57 



1-38 



trace 



014 



92-40 



4-85 



1-3S 



0-14 



1-23 



^ 



[This appears to be the same announced by Prof. Bailey. — See Min., p. 109.] 



pLUiiBO-sEsiNiTE [p. 431], — Under the name of nitch4:ocTcit€ fSuppl. Ill], Shepard 



has described (Min., p. 401) a mineral related to Plumbo-resinite. It occurs at the 



k Canton mine, Georgia, upon the joints of mica-slate, in thin coatings somewhat bo- 



f tryoidal, with the aspect of allophanc, and either white or bluish, yellowish or greea- 



* ish; transparent to translucent; streak uncolored. H.=2'75 — 3. G.==2-909. In a 



\ tube yields moisture. B.B. phosphoresces brightly but is infusible ; a rich blue color 



with nitrate of cobalt ; with soda yields zmc. Dissolves without effervcsceoce in 

 warm nitric or hydrochloric acid. Loses 29*45 p. c at full ignition. Inferred to be ^ 



a hydrated phosphate of alumina with oxyd of zinc. 



Dr. Genth's examinations (Am. J. Sci., xxiii, 424), obtained the following result. 

 G. (at 20° Gels.) about 4-014. With soda on charcoal yields lead and lead incrusta- 

 tions. Composition : 



th SI Fe f^ 



29-04 25-54 0'90 18-74 



24-69 0-68 



ft 



Ca 



C 



CI 



Insol. 



20-86 



1-44 



1-98 



0-04 



048: 



21-65 



1-49 







Ml 



99-02 



Oxygen ratio for ?b, E, P, fi, 2 08 : 1218 : 10 50 : 18-55. 



[The compound is analogous to that of plumbo-resinite, consisting of hydrated alu- 

 mina with phosphate of lead. But the proportions vary in the plumbo-resinite and 

 it is a question as to the definite compound it contains. The same doubt rests oTer 



the Canton mineral. 

 ^ Prof. Shepard has urged (Am. J. Sci., xxit, 41) that Dr. Genth had not a speci- 



^ men of the true Hitchcockite ; but Dr. Genth has confirmed his determinationa 



(ib. p. 133) with a specimen of the mineral recognized as such by_ Prof. Shepard. 



Plumbo-resinite, according to Prof. Shepard, occurs at the Canton mine. 



Damour in his paper on Plumbo-resinite (Ann. des Mines, [3], xvii, 191) shows 



that Berzc'lius must have precipitated the phosphoric acid along with the alumina 



and oxyd of lead, and so lost sight of it. In one respect, he observes, the analyses 



agree, — in the proportion of 1 : 1 between the oxygen of the water and alimaina, 

 * while the proportion of alumina varies. Daniour made three analyses of the 



Plumbo-resinite of Huelgoet agreeing in these respects; 



fb * Si fl 1^ Ca Pe S PbCl 



1. 35*10 34-32 18-70 8 06 0'80 0*20 0-30 2 27 = 99-73 



2. 62-15 11-05 6-18 12-05 25 8-24 = 99-92 



3. to 85 2-88 1-24 15-18 40 9-18 = 99-73 



1 



