THE TEREESTRIAL PERIDOTITES. — SEEPENTINE. 155 



cut by talcose (?) veins which are crossed by later chrysotile ones. The enstatite is 

 in part altered to the talc-like material, and in part to serpentine. It is probable that 

 olivine predominated over tlie enstatite when the rock was unaltered. This was pur- 

 chased from Voigt and Hochgesaug. 



Launceston, Tasmania. 



5170. A dark green rock, purchased of Ward and Howell, sprinkled with chromite 

 and talc scales. Weathers greenish-white. 



Section : greenish-gray with cloudy blotches. Composed of a pale yellowish fibrous 

 serpentine showing brilliant polarization, and altered enstatite crystals, talc scales, and 

 chromite. The talc is grayish-white, of feeble polarization, and usually associated with 

 the iron ore. In some cases it is dichroic, varying from a gray or yellowi.sh-gray to a 

 pale bluish tint. The enstatite in some cases retains its original plane of extinction, 

 although altered to a pale yellowisli serpentine mass. The cloudy spots are caused by 

 innumerable grains of iron ore locall}' concentrated. 



Windisch-Matre// , Tijrol. 



According to Von Drasche this serpentine is interbedded in a calcareous mica schist. 

 The color varies from a light green to a deep green or brown, and the rock is sprinkled 

 with calcite, asbestos, and chrysotile grains and fibres. Drasclie placed tlie specimens in 

 two divisions. 



1. Tliis is an olive-green rock ilecked with j-ellowish-brown spots, and contains 

 diallage, ankerite, and a white scaly mineral with irregular outlines. The section under 

 the microscope shows a groundmass formed from a compact network of a rhombic 

 mineral, which occupies the principal portion of the section. In addition grains of 

 magnetite and diallage were seen. Some talc was also observed. 



2. The other variety is a dark-green very fine-grained rock sprinkled with light-green 

 diallage crystals and white talc plates. Tlie section under the microscope is seen to 

 contain the network formed by tlio rliombic mineral, magnetite arranged in bands, 

 diallage, etc.* 



The section in the Whitney collection from Yoigt and Hochgesang, from this locality, 

 has the following cliaracters. Color pale green, but broken by veins and spots of black 

 iron ore. In polarized light the section shows the usual structure of a serpentinous rock 

 produced by the alteration of a peridotic one. It contains scales of talc and granular 

 masses of pyrite. Some of the iron ore is in forms resembling the picotite grains in the 

 Lake Lherz rock. These forms are traversed by fissures, and in reflected light it is seen 

 that the ore bordering them is crystalline showing metallic lustre, while the remaining 

 portions do not present these characters. The talc is so arranged that it appears to have 

 arisen from tlie conversion of enstatite material. The rock apparently contained originally 

 olivine, enstatite, and picotite at least. The section is traver.sed by veins of serpentine 

 and talcose material. 



St. Sabine, Vos(/es, France. 



5169. A greenish-black compact rock, weathering grayish-brown. 

 Section : pale green, and composed of serpentine in wdiicli a few altered enstatite 

 grains were observed. A few nodules occur which are formed in tlie interior of grayish 



* Mill. Mitth., 1871, i. 3-S. See also E. Hussak, Ibid., 1882 (2), v, 78-80. 



