THE TEERESTRIAL PEEIDOTITES. — SERPENTINE. 153 



Waldhcim, Saxony. 



5002. A dark grayish-green rock, purchased from Yoigt and Ilochgesang, mottled 

 with spots of ligliter grayisli-green, and containing cliromite. 



Section : greenish-gray with a reticulated network of iron ore. Chiefly composed of 

 clear colorless or pale yellow and pale green serpentine. This retains in part the structure 

 of the fissured olivine, and in part that of the enstatite crystals whicli it has replaced. 

 In the latter, the plane of extinction is the same as that of the enstatite, while in the 

 serpentine replacing the olivine we have the reticulated network following the fis.sures, 

 with the polarization of the .serpentine first formed along the fissures difteriug from that 

 later replacing the central portions of the grains. This difference is to some extent 

 observable in common light, so that one is able to trace out the forms of the original en- 

 statites, and then those of the olivine grains which were enclosed in them. The structure 

 of the rock thus revealed shows that it was originally composed principally of olivine 

 with comparatively small amounts of enstatite. 



The Wakllieim serpentines have been studied by Dathe, who describes that from the 

 Tunnel as a blackisli-green stone holding small garnets and many clear vitreous points. 

 The section is composed of well-marked olivine grains, with tlie secondary serpentine, 

 magnetite, garnet, picotite or chromite, and diallage. That from tlie Quarry on the Gebers- 

 bach is a dark-green serpentine showing olivine grains. In the section the olivine shows 

 various degrees of alteration to an ore-bearing serpentine, forming tlie usual reticulated 

 network. It also contains diallage and garnet, the latter of which is sometimes altered 

 into chlorite. The serpentine Irom the Brcitcnhcrg is of two kinds: one a dark green 

 serpentine, hard and brittle, and carrying garnet, and the other softer, tougher, and 

 wanting garnets. The former answers in character to the Tunnel and Quarry sei-pen- 

 tines, while the latter shows the network structure of serpentine, and holds iron ore and 

 enstatite (bastite).* 



KoJcMno-Nero, Thessali/. 



Dark, nearly black compact rock, traversed by strings of yellowish-green fibrous ser- 

 pentine. In the section it shows the usual network of serpentine associated with altered 

 diallage or enstatite crystals. 



Similar to this is a rock from Polydcndri which contains both altered diallage and 

 enstatite, as well as garnet and picotite grains. 



A similar rock from Xcokhori shows comparatively fresh diallage traversed by fine 

 parallel fissures along which are arranged small needles and plates.f 



Between the Rivers Dajao and Cembi, Province of Santiago, Sun Domingo. 



120 G. A dark-brown rock flecked with greenish spots. Contains a little talc, and 

 is traversed by serpentine veins having greenish borders and a dark central line owing 

 to the iron ore in it. (W. M. Gabb, Collector.) 



Section : banded greenish-yellow and black. The greenish-yellow portions are seen to 

 be composed of yellowi.sh pseudomorphs of serpentine after olivine, traversed by fissures 

 and surrounded by a network of whitish fibrous serpentine with the fibres arranged per- . 

 pendicular to the course of tlie veinlets. In other portions the remains of some apparent 

 pyroxenic mineral occurs, while elsewhere the serpentinous material is quite compact, but 



* Neues Jahr. Miu., 1876, pp. 239-243. f Becke, Min. Mittb., 1S78 (1), i. 472, 473. 



20 



