68 E. V. Shannon — Mullanite, a new Member of the 



which seems to cut the main mass of the vein. The mul- 

 lanite and the epiboulangerite look exactly alike in the 

 hand specimen, being distinguished from each other only 

 by their streak and in what proportion they occur is not 

 known. Of five specimens examined, only one consisted 

 of epiboulangerite, which, therefore, is believed to be 

 somewhat rarer than mullanite. There is no indication 

 that the epiboulangerite is secondary or an alteration 

 product of the mullanite. ' 



In the Gold Hunter Mine, mullanite is a constant,, 

 though not abundant constituent of the ores. It has for 

 years been thought to be stibnite. Ransome, 2 writing 

 about 1905, gives the following: "Stibnite (=mullan- 

 ite) has been found, in this district, only in the Gold 

 Hunter Mine and in a neighboring prospect, the Enter- 

 prise. In the Gold Hunter the stibnite forms small 

 needles or acicular clusters in quartz, or, more rarely, in 

 siderite. In some of the quartz, the needles project into 

 little vugs. The mineral occurs sporadically in the 

 quartzose parts of the lode, usually near the hanging 

 wall." This so-called stibnite seems to be the sul- 

 phantimonite, mullanite. Whether the mineral men- 

 tioned by Ransome from the Enterprise prospect is the 

 same is not known. Material, indistinguishable from 

 mullanite in appearance, from the Greenhill-Cleveland 

 Mine contains only 36.4% lead and is probably jameson- 

 ite. A similar mineral from the Bunker Hill & Sullivan 

 Mine contains lead in unknown proportion. The two 

 mines in which mullanite occurs, although near 40 miles 

 apart, are strikingly similar in many respects. The 

 veins are inclosed in rocks of the same geologic forma- 

 tion. 



Description. — The specimen from the Iron Mountain 

 Mine consists of an aggregate of long, parallel, steel-gray 

 fibers. In the lower end of the specimen, a rounded 

 crystal of quartz is embedded. The fibers of mullanite 

 curve around this quartz fragment which has somewhat 

 the appearance of a water-worn pebble. Needles of mul- 

 lanite occur also imbedded in the quartz. At the upper 

 end of the specimen the needles project into an open 

 cavity and are squarely truncated by a flat plane. The 

 aggregate of fibers is friable and can be easily broken up> 

 with the fingers. 



2 Prof. Paper, U. S. Geol. Survey, No. 62, p. 92. 



