418 JULIEN 



to prove that the mineral serpentine, played but a small part in 

 constitution of his materials. 



The analysis of a serpentinoid from Kallerangen ^ is pre- 

 sented above, as offering a close analogy. That rock occurred 

 in association with hornblende schists and gneisses, chlorite and 

 talc schists, and was pronounced a decomposition product of an 

 aggregate of aluminous tremolite, olivine, and in places bron- 

 zite. All of these minerals, together with magnetite, chromite 

 and newly formed chlorite, survived in microscopic particles, 

 and a netted structure prevailed through the thin sections. 



A similar composition is shown by a serpentinoid (D) from 

 Lower Predannack in the Lizard district of Cornwall, England, 

 a reddish banded rock, rich in parallel crystals of colorless 

 amphibole. Under the microscope it presented the mesh struc- 

 ture of olivine, and, in some specimens, evidences of enstatite 

 or bastite, and has been recognized as a derivative from a fine- 

 grained peridotite.^ 



Between the long-discussed hornblende schists and ** serpen- 

 tines " of the Lizard district and those of the region near 

 Manhattan Island, certain marked points of difference offer 

 themselves. Here the rocks of both classes are decidedly 

 homogeneous, schistose but not banded, blending together in- 

 sensibly and often intimately intermixed, and retaining abundant 

 indications of an actinolitic constitution which preceded the 

 alteration into serpentinoid. They seem to be allied to the ser- 

 pentine sheets but not to the banded hornblende schists of 

 Porthalla in the Lizard district, and to correspond closely to 

 some of the interesting examples of passage of igneous rocks 

 into "serpentine," in the extra- Lizard district, in the west of 

 England, whose phases of alteration have been displayed in 

 numerous published analyses.^ 



Serpentines from North Syria, ^ derived from alteration of 



' George Schulze, " Die Serpentine von Erbendorf in der bayerischen Ober- 

 Pfalz," Inaug.-diss., Berlin, 1883, 21. 



2T. G. Bonney, Quart. Jour. Geol. Soc, XXXIV, 1877, 915, and XLVII, 

 1891, 472. 



3 J. H. Collins, Geo/. Mag. (Dec. Ill), 1886, 360-566, and IV, 1887, 220-226. 



*P'inckh, loc. cit.y 125-126. 



