G. P. Merrill— Ophiolite of Warren Co., JSf. Y. 191 



pyroxene granules, I can but suggest that we have in this alter- 

 ation the source of the serpentinous material and that the " min- 

 eral pyroxene of the white or colorless variety . . occurring 

 often in the lower layers and filling some of the canals " of the 

 Eozoon, is but the residual mineral which has escaped alter- 

 ation. Further, that the structureless nodules of serpentine 

 found in the eozoonal rocks, and to which often patches of 

 Eozoon are attached or imbedded, are but patches in which the 

 alteration is complete and the pyroxenic nucleus quite obliter- 

 ated. Dr. Dawson, although recognizing the frequent accom- 

 paniment of a white pyroxene with the eozoonal structure, in 

 no case mentions appearances indicating that the serpentine is 

 an alteration product, but seems rather to regard it as an orig- 

 inal injection,* following in this respect the well known teach- 

 ings of Dr. Hunt.f Those conversant with the literature of 

 the subject may recall that Messrs. King and B,owney;f: recog- 

 nized also the presence of pyroxenes in these limestones and in 

 insisting upon the inorganic nature of the eozoon, compared its 

 structural forms to those assumed by chondrodite, coccolite, etc. 

 in the limestones of New York, New Jersey and other local- 

 ities. These authorities seem however to have regarded the 

 serpentine as true " replacement pseudomorphs " after these 

 minerals rather than alteration or metasomatic products. 



In conclusion : The serpentine in the Warren County Ophi- 

 olite, Ophicalcite or Verdantique as it has been variously called 

 is an alteration or metasomatic product after a mineral of the 

 pyroxene group. The original rock would appear to have been 

 simply a pyroxenic limestone, the pyroxene occurring either in 

 scattering granules or in granular aggregates of considerable 

 size. An examination of the Essex County Ophiolite reveals a 

 somewhat similar, though more complicated condition of affairs. 

 A portion of the serpentine here is also derived from a pyrox- 

 ene, but another, and in cases a very large portion is apparently 

 after a mineral which I have not as yet found sufficiently 

 unchanged to be able to identify. The rock is as yet insuffi- 

 ciently studied, and must be made the subject of another paper. 

 I am indebted to Mr. George F. Kunz for the Warren County 

 material. 



National Museum, Dec. 18, 1888. 



*Op-cit., p. 16-22 et als. 



f Quart. Jour. Geol. Soc. of London, vol. xxi, p. 67, Chem. and Geol. Essays, etc. 

 \ Quart. Jour. Geol. Soc. of London, vol. xxv, p. 115: also Proc. Royal Irish 

 Academy, vol. x, Part IV, 1870, p. 506. 



