178 PERIDOTITE. 



and of a deep reddish-brown color. The remainmg portions are crystalline- 

 granular, with a dull lustre. The Texas (Pa.) chroniite in the sections is 

 mainly opaque and traversed by fissures filled with serpentine. The surface 

 of the chromite is rough, crystalline-granular, and the lustre dull ; but in the 

 thinnest portions the mineral is translucent and of a brown color. The 

 powder in the thin portions is translucent and of a greenish and reddish- 

 brown color. The color of the massive chroniite is velvety black, and it has 

 a resinous to vitreous lustre, like the chromite from North Carolina. The 

 mineral in the serpentine from Windisch-Matrey (Tyrol) is mostly opaque 

 and filled with magnetite, but a little of it was seen to be translucent and of 

 a brownish color. The mineral in the Franklin (N. C.) peridotite is entirely 

 opaque in the thin section, and its surface shows a dull lustre, is black, rough, 

 and granulated ; but its powder is translucent and of a deep yellowish-brown 

 color on the thin edges. 



The ores in the Herborn (Nassau) picrite are all opaque. Part have a 

 bluish reflection, and part a dull one. The grains are in part mixed with 

 pyrite. A brownish translucence seen at the borders of the ores in a few 

 cases, is here considered to be owing to the coloration of the adjacent 

 silicates by the iron oxides. 



In the peridotites (mostly serpentines) from Gj(/)rud and Christiania, 

 Norwa}^; Elba; Presque Isle and Ishperning, Michigan; Westfield and 

 Lynnfield, Massachusetts ; High Bridge, Ne-w Jersey; Newport, Vermont; 

 Deadwood, Hepsidam, Chip Flat, and Depot Hill, California; numbers 120 

 G. and 252 G., San Domingo ; and Tasmania, the ores seen are all opaque, 

 while part are undoubtedly magnetite. 



The general characters of the chromites or picotites and other iron ores 

 in the peridotites of the " Assos Expedition " are as follows : A. E. 324 has 

 the centre of one grain of a yellowish-brown color with a velvety reflection. 

 The border is granular, opaque, and traversed by fissures filled with serpen- 

 tine. Some of the other grains are reddish-brown, and translucent in spots ; 

 the remaining portions of these grains, and the entire mass of the remaining 

 grains are opaque. 



A. E. 265 has its chromic ores in grains and octahedrons, which are trans- 

 lucent and of a deep brown color. They show a brilliant bluish lustre in 

 reflected light. 



A. E. 207 has part of its grains translucent on the thin edges, and of an 

 orange-brown to a deep cherry-red color ; while the remaining grains are 



