Brush and Dana — Mineral Locality at Brrniokville, 203 



alteration-products, show in part what was accomplished. In 

 addition to what is mentioned in these papers, the locality has 

 iral different times yielded a not inconsiderable amount 

 of nraninite, in part in octahedral crystals with a specific 

 gravity of 9*3; this bag been investigated chemically by Oom- 

 Btock. With the nraninite have been found two or more 

 uranium phosphates which have not as yet been thoroughly 

 studied. Oolumbitc has also been found in considerable quan- 

 tity, aggregating more than 500 pounds. This occurs in 

 crystalline masses, and in part well developed crystals and 

 tips of crystals in parallel position of remarkable size. It 

 lias a specific gravity of 5'73, and as shown by an analysis by 

 T. B. Osbornef contains L9S3 per cent of Ta 2 () 6 . Another 

 kind of columbite has also been found in minute reddish brown 

 translucent crystals usually implanted upon the spodumene.f 

 This variety Comstock has shown to be exceptionally inter- 

 esting in the fact that it contains manganese with practically 

 no iron, and further lias the niobium and tantalum in the ratio 

 of 1:1; it has a specific gravity of 659. Other points of 

 interest that have been brought out are the occurrence on a 

 rather abundant scale of a mineral, both massive and indistinctly 

 fully crystallized, which resembles cyrtolite but has not yet been 

 investigated; also of smoky quartz, in part well crystallized, 

 and remarkable for its richness in fluid inclusions (C0 2 , etc.) as. 

 described microscopically and chemically by Hawes and 

 Wright ;,^ also of beryl in large columnar masses sometimes 

 two feet or more in length; still further of albite in finely 

 crystallized specimens. Apatite has been found in a variety 

 of forms ; one variety, of a dark bluish green, has been found 

 by Penfleld to contain 10*6 per cent of MnO. Other kinds 

 are interesting crystallographically and resemble the Swiss 

 crystals in habit and complexity. Mica has been obtained in 

 limited amount of a merchantable form (300 pounds of plates 

 cut to pattern) ; the most common variety, however, is that 

 occurring in curved plates, presenting a smooth convex surface 

 like a watch-glass ; these aggregates have a radiated as well as 

 concentric structure. Specimens of the Branchville mica have 

 been analyzed by Rammelsberg.* 



The most important developments, however, have been those 

 of the summers of 188S and 1S89, when considerable quantities 

 of the manganesian phosphates were brought to light. This 

 result has been especially gratifying to us, since it has given us 

 specimens of all but one of the new species described in 1878 

 (cf. p. 202), several of which we had almost despaired of 



* This Journal, xix, 220, 1880. I This Journal, xxx. 330, 1885. 



\ Ibid., xix, 131, 1880. § Ibid., xxi. 203, 209, 1881. 



|| Ibid., xix, 307, 1880. • Jabrb. Min.. ii, 221. 1885. 



