THE TEllllESTRlAL PERIDOTITES. — SEUI'ENTINE. 159 



Kbpfhcrf/, Austria. 



This rock, according to Dr. F. Becke, is a light green to dark porous soft stone, bearing 

 long, colorless tremolite crystals, chrome-bearing magnetic ore, and numerous soft silver- 

 white talc scales. The rock is greatly altered, and in the section shows the usual net- 

 work, arising from the alteration of olivine, which in the darker stone still exists in single 

 grains, but in the light green specimens the olivine has disappeared, and grains of a 

 rhombic carbonate appear in its place.* 



Nezeros, Thcssalf/. 



A dark, nearly black rock, rich in cliromite, has been described by Dr. F. Becke as 

 showing in the thin section the usual mesh structure formed by the serpentine and iron 

 ores. It also contains a little colorless actinolite, possessing the prismatic cleavage of 

 hornblende. t 



Fatu Temanu, Timor. 



A dark bluish-green rock with light green spots and magnetite grains. Microscopi- 

 cally this serpentine evidently was derived from olivine, and it shows a characteristic 

 network especially marked through the arrangement of the ore particles which form the 

 medial lines. Bordering them are light green bands enclosing tlie darker-colored inter- 

 stitial portion. Much chrysotile occurs, and a whitish-green picrolite, forming in the 

 section a finely fibrous cloudy mass. I 



Four miles from Wesifield Centre, Westfield, Massachusetts. 



1073. Section: greenish-yellow with grayish-white 'spots, and traversed by an irreg- 

 ular network formed from dust, grains, and crystals of black iron ore. The serpentine in 

 polarized light shows aggregate and fibrous characters, while dolomite occurs sprinkled 

 througli much of the section's mass. The grayish spots seem to be formed of dolomite 

 mixed with serpentine and talc. 



The hand specimen is a dark grayish-black rock, with light greenish irregular patches 

 of serpentine, talc, and dolomite. This structure is similar to that of the other specimens, 

 1074, 1075, 1076, 1077, 1078, and 1079. In the weathered surface forms the talc is 

 better crystallized, showing its normal structure, while the dolomite is more abundant and 

 better marked. In these specimens every gradation can be traced between the light- 

 greenish serpentinous colloid-like masses to the well-differentiated aggregations of talc 

 plates. These specimens show clearly the production of talc, dolomite, and serpentine 

 from the metamor})hosis of peridotites. 



This rock (1073) weathers to a rough deep-pitted surface, colored grayish and coated 

 with lichens. Here the difference is strongly marked between the internal molecular 

 alterations and the superficial surface weathering. 



I have been greatly indebted to the kindness of Mr. S. H. Dean, of High Bridge. X. J., 

 for this and many others of the serpentines of Eastern North America ilescribed here. 



1074. This section is similar to that of No. 1073. The iron ore forms in places 



* Mia. Mitth., 1882 (2), iv. 341-343. t ^in. Mittb., 187S (1). i. 4ri)-t72. 



% Wicliniann, Jaarb. Mijiiw. N. 0. 1., 18S2, pp- 214-216. 



