4:6 Rogers — Miner 'cdogical Notes. 



the symmetry of the crystal. The diploid is sometimes lack- 

 ing and occasionally the pyritohedron and octahedron are in 

 equal development, the crystals then simulating the regular 

 icosahedron of geometry. On account of striations good 

 images were not obtained, and in the case of the diploid the 

 reflections had to be relied upon. The measurements are as 

 follows : 



Average. Calculated. 



M a o 432 A HI V 15° 16' 15° 13^' 



e ^ 210 ^ 111 3 39° 14' 39° 14' 



e A e 210 A 210 3 ' 53° 29' 53° 7f 



4. A Topaz Crystal of Unusual Habit from Pike's Peak. 



A topaz crystal from Pike's Peak, Col., measuring (25X20X 

 15 mm ) diifers in habit from most of the described crystals. See 

 figure 6. The forms present are c (001), b (010), m (110), ' 

 I (120), y (021), y (041), and a small undetermined pyramid of 

 the unit series. I and y are the dominant forms and the crys- 

 tal is lengthened in the direction of the a-axis. m and I are 

 vertically striated and the other faces are dull. The forms 

 were identified with the contact goniometer, 



5. A new locality for JLeadhillite. 

 The rare mineral leadhillite has been reported from but 

 three localities* in this country. The writer here records the 

 mineral from a new locality, namely the Cerro Gordo Mines, 

 Inyo Co., Cal. It occurs as small imperfect crystals of a pale 

 sea-green tint on a specimen associated with linarite and caled- 

 onite. The crystals are short prismatic or thick tabular, 

 of hexagonal aspect, much resembling those from Granby,t 

 Missouri. The following forms were observed : o (001), 

 m (110), a (100), and a narrow face in the vertical zone which 

 could not be identified on account of its small size. The crys- 

 tals were not suitable for measurement. There is perfect 

 cleavage parallel to c and the cleavage plates have a high 

 pearly lustre. The mineral is soluble in HN0 3 with efferves- 

 cence leaving a white residue. 



6. Linarite Crystals from California. 

 Iflo linarite crystals have been described from the United 

 States though it is known to occur at three localities.^ The crys- 



* Xewberry Dist., Spartanburg Dist., N. C, by Shepard, Dana Mia. 6th edit , 

 p. 922, 1892. Schultz Gold Mine, Arizona, by Peofield, ibid. Granby, Mo., 

 Pirsson and Wells, this Journal, vol. xlviii, p. 219-226, 1894. 



\ Pirssou and Wells, loc. cit. 



\ Cerro Gordo mines, Inyo Co., Cal., Dana's System, 6th edition, p. 925 r 

 1892. Stevenson Bennett mine, near Las Cruces, New Mexico, Farringtou, 

 Publications Field Columbian Museum, Geol. Series, vol. i, no. 7, p. 225, 1900. 

 Galena, Kansas, Rogers, Kansas Univ. Quarterly, vol. ix A, p. 165, 1900. 



