Williams — Con tact-metamorjihism^ near Peekskill. 265 



both as regards actual contact and inclusions, are much alike at 

 the two localities — a fact that has already been noted by Pro- 

 fessor Posenbusch. * 



Contact-phenomena have been so rarely studied in the crys- 

 talline schists that mention should also be made in this connec- 

 tion of the unusual mineral aggregates which were first 

 observed by Professor Lossen in the kersantite of Michaelstein 

 in the Harz Mountains.f These have recently been carefully 

 studied by Dr. Max Koch of Berlin,;); who suggests, as the 

 most probable explanation of their anomalous character, that 

 they are metamorphosed inclusions of crystalline schists. There 

 are important individual differences between the Michaelstein 

 and Cortlandt inclusions, but yet there is sufficient resemblance 

 both in structure, mode of occurrence and mineral composi- 

 tion, to make it certain that the two belong to the same general 

 category.§ 



For the sake of comparison a list of the metamorphic min- 

 erals (exclusive of quartz, f elds'par and biotite, which are 

 common to all), which have been observed at the three above 

 named localities is here appended : 



Cruger's. Michaelstein. Klausen. 



Sillimanite, sillimanite, 



cyanite, cyanite, 



garnet, 

 stauroiite, 



anclalusite. 

 garnet. 



spinel, 

 corundum. 



tourmaline. 



pleonaste. 



corundum. 



rut ile, 



anatase, 



ilmenite, 



zircon, 



magnetite, 



hypersthene, 



r utile. 



ilmenite. 

 zircon. 



garnet, 

 stauroiite, 

 tourmaline, 

 pleonaste, 

 corundum, 

 margarite, 

 ripidolite, 

 rutile, 

 sphene, 

 ilmenite, 

 zircon, 

 magnetite, 



pale augite (on contact), 

 scapolite (on contact), 

 zoisite, calcite, j several undeter- ) 



epidote. apatite. \ mined minerals, j 



18 species. ]4 species. 9 species. 



* Mikroskopische Physiographie der massigen Gesteiue. 2d ed., p. 128. 



f Geologische und petrographische Beitrage zur Kenntuiss des Harzes. Jahrb. 

 d. kon. preuss. geol. Landesanstalt fur 1880. 



% Die Kersantite des Unterharzes, 1 Theil . ib. for 1886, pp. 44-104. 



§ The writer is indebted to Dr. Koch for an interesting suite of specimens illus- 

 trating the various kinds of inclusions found in the Harz kersantites. A studjr 

 of these shows many points of difference, but nevertheless a strong general like- 

 ness to the Cortlandt inclusions. 



