82 LITHOLOGICAL GEOLOGY. 



by T. S. Hunt, has the composition of ordinary chlorite. (Logan's 

 Eep. for 1853-56.) 



(6.) Serpentine (§ 66). — A massive uncleavable rock, of dark-green 

 to greenish-black color, easily scratched with a knife, and often a 

 little greasy to the feel when a surface is smoothed. Although 

 generally of a dark-green color, it is sometimes pale grayish and 

 yellowish green, and mottled. 



A serpentine rock containing diallage is the gabbro of the Italians. 



(7.) Schillerite, or Schiller rock, Diallage rock. — A dark-green to greenish- 

 black rock, made up of Schiller spar, and having the following composition : 



1. Kb'hler; 2, T. S. Hunt (Logan's Rep., 1855-56, 443); 3, id. of the pure 

 diallage : — 



Si03. A1203. FeO. MgO. CaO. NiO. MnO. HO. 

 1 43.90 1.28 13.01*26.86 0.54 12.43 Kbhler. 



2. Canada 41.80 6.80 11.05 26.13 7.00 trace 7.60 Hunt. 



3. Canada 47.15 3.45 8.73 24.56 11.35 trace 5.82 Hunt. 



It is often associated with serpentine, chlorite, and talc-schist. 



(8.) Ophiolite (or verd-antique marble). — A variegated mixture 

 of serpentine and either carbonate 'of lime {calcareous ophiolite), do- 

 lomite (dolomitic ophiolite), or carbonate of magnesia or magnesite 

 (magnesitic ophiolite). Color, dark green, mottled with lighter green 

 or white. 



It often contains chromic iron sparsely disseminated through it, forming 

 kregular, black, submetallic spots ; also some talc, asbestus, sahlite ; and analysis 

 often detects nickel as well as chrome. T. S. Hunt has found both nickel and 

 chrome in the serpentines or ophiolites of the Green Mountain range, in those 

 of Roxbury, Vt., New Haven, Ct., Hoboken, N. J., Cornwall, England, Banff- 

 shire, Scotland, Vosges, France. They occur also in the pyrosclerite and Wil- 

 liamsite of Chester co., Pa., and in the antigorite of Piedmont. Hunt found 

 no nickel in serpentine from Easton, Pa., Montville, N.J., Philipstown, N.Y., 

 Modum, Norway, Newburyport, Mass., and none from the Azoic series of rocks. 



5. Hydrous Aluminous rocks. 



87. These rocks consist largely of agalmatolite or pyrophyllite, and have a 

 close resemblance to talcose and serpentine rocks in feel, hard^ss, and ap- 

 pearance. 



Pargphite. — Essentially agalmatolite ($ 67) in composition. Its fine-grained 

 texture and somewhat soapy feel are its striking peculiarities. It occurs both 

 as a slate and rock. The name was first given by T. S. Hunt to a variety 

 occurring in northern Vermont, and alludes to a resemblance in aspect to ser- 

 pentine. The dysyntribite of Shepard, found in northern New York (§ 67), 

 is a rock variety. 



* With some oxyd of chrome. 



