300 O. 0. Farrington — Azurite from Arizona. 



Art. XXXV. — On Crystallized Azurite from Arizona ; by 

 O. C. Farrington. 



Crystals of azurite from Arizona, remarkable for their 

 number and brilliancy, have for a long time been abundant in 

 collections, but so far as we know no detailed crystallographic 

 study has yet been made of them. The monograph of Schrauf 

 published in 1871," contains no reference to any specimens 

 from this locality, the only American crystals mentioned being 

 some from Venezuela. Mr. Oliver W. Huntington has de- 

 scribedf crystals from Clifton, Arizona, elongated in the direc- 

 tion of the orthodiagonal, a habit which will be referred to 

 later. On these crystals twelve forms were identified, but the 

 crystals, he states, were not suitable for accurate measurement. 

 No further study of the Arizona crystals has been made as far 

 as known. 



With a view, therefore, of ascertaining the chief types or 

 habits into which these crystals group themselves as compared 

 with European azurites, and of obtaining as much data as pos- 

 sible toward establishing an exact axial ratio, the writer has 

 made an investigation of them, with material very kindly 

 placed at his disposal by Profs. E. S. Dana and S. L. Penfield. 

 Altogether twenty-one forms were observed on the Arizona 

 crystals, and these are given in the following table, the four 

 marked by an asterisk being new. Previous to this a total 

 number of 54 forms had been observed. The symbols are 

 given in accordance with the position for azurite adopted by 

 Haidinger, Miller and Dana. 



c, 001, 



0, 101, l-l 



h, 221,-2 o, 241, 4-2 



a, 100, i-l 



V, 302. \-i 



7, 121,-2-2 *G, 321, 3-| 



m, no, / 



I, 023, £-* 



*JV; 44?, \ *K, 1210-5, ^-; 



W, 120, i-2 



/. 011, 1-i 



x, 111, 1 



a, 101, — 1-i 



p, 021, 2-1 



k, 221, 2 



F, 207, H 



*Q, 223, -f 



e, 245, f-2 



Fig. 1 shows a basal projection of these forms, from which 

 the principal zonal relations can be determined. The size 

 given to each face indicates its relative 

 importance, and it will be noted that but 

 a small number of forms occur in the 

 negative quadrants. 



It was found that all of the crystals 

 examined could be referred to one or 

 the other of four principal habits, which 

 may be designated as the pyramidal, pris- 

 matic, dome-like and lath -like habits, the 



♦Sitzungs Berichte, Vienna, Akad., June and July, 1871. 

 fProc. Amer. Acad. Arts and Sci., 1885. 



