Lindgren and Hillebrand — Minerals from Arizona. 459 



Spangolite (H 18 Cu 6 AlClS0 19 ). — This peculiar mineral, essen- 

 tially a highly basic chloro-sulphate of copper and alumi- 

 num, was discovered and described by Prof. S. L. Penfield* 

 some fifteen years ago. The specimen came from some point 

 within 200 miles of Tombstone, Arizona, and probably from 

 one of the great copper camps of the territory. Somewhat 

 later it was identified by Prof. H. A. Miers on two specimens 

 from Cornwall, England, but the American locality has not 

 yet been found. It is, therefore, a matter of interest to record 

 its discovery on some specimens from the Metcalf mine of the 

 Arizona Copper Company, taken from the workings in the 

 great open cut not more than 100 feet below the surface. 

 These specimens consist of white sericitized granite-porphyry, 

 in part silicified, and traversed by veinlets and irregular masses 

 of cuprite ; the cuprite contains native copper and is covered 

 by crusts of malachite, brochantite, and chrysocolla. A soft 

 and scaly bluish green coating on the chrysocolla proved to 

 consist of microscopical hexagonal crystals or cleavage foils, 

 remaining dark between crossed nicols. The mineral was 

 identified as spangolite, a determination in which Professor 

 Penfield concurred. No measurable crystals were found and 

 the mineral is very inconspicuous. It is difficult, if not impos- 

 sible, to obtain material entirely free from accompanying 

 minerals. 



Selected bluish flakes from this specimen gave tests for water, 

 and the sulphate and chlorine ions, besides copper. There was 

 too little of this pure material to permit of a test for alumina, 

 but the mixed copper minerals composing the greater part of 

 the specimen showed the presence of this body. It seems 

 therefore probable on these grounds alone that the bluish flakes 

 are spangolite. Vanadium, phosphorus, and arsenic are absent. 



The closed-tube reactions of the mixed copper minerals are 

 very striking. Water is given off first. Then appears sud- 

 denly a white sublimate (A1C1 3 ?) near the assay, which seems to 

 form or at once change to minute colorless drops. This deposit 

 can be driven slowly up the tube, followed at its lower, sharply 

 defined edge, by dark yellow-brown drops (CuCl 2 ?), which on 

 cooling solidify to greenish crystalline aggregates, and the 

 part of the tube between them and the assay shows under the 

 lense delicate feathery crystallizations like frost markings on win- 

 dow panes. Down in the flame the glass becomes colored red 

 (Cu 2 ?) and in parts yellow. On charcoal the blowpipe flame 

 is colored azure blue and at the same time green. 



In order to compare the above closed-tube behavior with that 

 of undoubted spangolite, a small fragment of the latter, offered 

 by Dr. Penfield, was tested. It gave water and then a white 



*This Journal, 1890, vol. xxxix, pp. 370-378. 



