190 G. P. Merrill— OphioUte of Warren Co., N. T. 



Museum collections, sometimes carry a white nucleus. The 

 presence of this nucleal material, which may frequently be 

 observed passing by imperceptible gradations into the green 

 serpentinous material, suggested at once that here, too, the ser- 

 pentine is a metasomatic jjroduct, as the writer has shown* is 

 the case with that of Montville, New Jersey. Thin sections 

 of the rock under the microscope confirm this suggestion. The 

 white nucleal mineral is seen to be an aggregate of small mono- 

 clinic pyroxenes, quite colorless in the thin sections, without 

 pleochroism, but polarizing brilliantly and giving extinctions 

 on clinopinacoidal sections as high as 41°. Irregular canals of 

 serpentinous matter cut through these aggregates following 

 cleavage and fracture lines, and all stages of alteration can, as 

 in the Montville stone, often be observed in a single section. 

 In the more even-textured portions of the rocks the serpentine 

 appears as rounded or oval granules with small enclosures of 

 secondary calcite imbedded in the large original plates of the 

 same material. Here, too, all stages of alteration are readily 

 detected, some of the pyroxene granules being traversed by but 

 a few wavy threads of the serpentinous matter, while in others 

 not a trace of the original mineral longer remains. Were it not 

 for these fresh remaining portions one would hesitate to pro- 

 nounce them pyroxenic derivatives, since they in no case show 

 crystal outlines, but are mere oval blebs or granules imbedded 

 like shot in the white calcite in a manner quite similar to that 

 of the chondrodite grains in the white limestone from Amity, 

 Orange County, in the same state. The grannies are not in 

 all cases isolated but sometimes occur in groups, or connected 

 by canals of serpentinous matter in a manner strikingly sug- 

 gestive of the detached sections and groups of Eozoon cham- 

 berlets as figured by Dr. Dawson on pages 24 and 28 of his 

 late paper. f Indeed I can but feel, since reading his re- 

 sume that, even at this late day, this serpentinization of py- 

 roxene is destined to throw some light on the Eozoon prob- 

 lem. This idea is supported by the fact that the fragmental 

 Eozoon has been reported from these same formations at War- 

 ren County, further by Dr. Dawson's statement that eozoonal 

 masses often occur as " rounded or dome-shaped masses that 

 seem to have grown on ridges or protuberances, now usually re- 

 presented by nuclei of pyroxene.";}; While from the study of 

 so limited an amount of the Warren County stone it may not 

 be advisable to assert that the remarkably regular structures 

 figured by Dr. Dawson are due wholly to alteration in situ of 



* Proc. U. S. Nat. Mus.. vol. xi. 1888, p. 105. 



f Specimens of Eozoon Gauadense and their Geological and other relations. 

 Peter Redpath Museum. Notes ou Specimens, Sept. 1888. 

 % Op-cit, p. 29. 



