0. H. Warren — Mineralogical Notes. . 369 



Art. XXX\.— Mineralogical Notes ; by C. H. Warren. 



The minerals which are described in this paper were pre- 

 sented for the purpose of study to the Mineralogical Labora- 

 tory of the Sheffield Scientific School by the gentlemen whose 

 names appear beyond, and to whom the writer takes pleasure 

 in expressing his thanks. The materials were kindly placed at 

 the writer's disposal by Prof. S. L. Penfield, and the investi- 

 gations were made in the Sheffield Mineralogical Laboratory 

 while the writer was connected with that institution. 



Anorthite Crystals from Franklin Furnace, N. J. 



The first specimens received, showing the anorthite crystals, 

 were found by Mr. Wm. Niven, of New York City, in the 

 limestone quarry near the railroad station, at Franklin, and 

 later some of the same mineral was received from Mr. Hancock, 

 of Burlington, N. J. The crystals are of a dull gray color, 

 tabular in habit and vary in size from individuals a few milli- 

 meters in diameter to large flat tables, l^ cm long, l cm wide and 

 2 to 3 mm in thickness. They are few in number and are 

 imbedded in the white crystalline limestone characteristic of 

 that region. Flakes of graphite are plentifully sprinkled 

 through the limestone and are plainly visible in the anorthite 

 crystals themselves. As stated by Mr. Niven, the position in 

 the quarry from which the specimens came was close to the 

 contact of the limestone and the granite, and it is interesting to 

 note here that anorthite has been noticed by Lacroix* as a 

 contact mineral in limestones of the Pyrenees. It is probable 

 that the Franklin mineral is of similar origin. 



Although the faces of the crystals are dull and their solid 

 angles and edges are somewhat rounded, sufficiently good 

 reflections of the signal were obtained on some of the crystals 

 to identify the following forms : 



c 



001, 



m 110, 



y 



201, 



b 



010," 



M 110, 



p 



111, 



111. 



Below are given the measured angles with the correspond- 

 ing values calculated from the fundamentals established by 

 Marignac.f 



* Carte Geoligique de la France. No. 64, vol. x, 1898-9. 

 fKk., Mm. Kussl., iv, 200, 1862. 



