334 Mr. T. S. Hunt on the Composition and Metamorphoses 



Eastern To\\Taships have shown that the serpentines of that 

 metamorphic region belong to Lower Silurian strata, of which 

 these rocks at St. Nicolas are the stratigraphical equivalent, it 

 was hoped that a chemical examination of them, and a compa- 

 rison between the altered and unaltered shales, would throw 

 some light upon the nature of that mdely-spread metamorphism, 

 and upon the origin of serpentine. The results obtained were 

 different from what was expected, but are not, however, without 

 interest. 



In the immediate vicinity of the intrusive rock thin layers of 

 the shale are changed into a greenish translucent material, which 

 is sometimes an inch in thickness. The surfaces of the sand- 

 stone in contact with the shale seem to have undergone a similar 

 change, or at least to be covered with a film of the green trans- 

 lucent mineral, and they often exhibit a concretionary or mammil- 

 lated surface. In one instance the thickening of a stratum of 

 shale forms a mass several inches in diameter, which is earthy 

 and opake within, but upon the surface next to the overlying 

 rock assumes the serpentine-like chai'acter alluded to ; and in a 

 continuation of the layer, where it becomes thinner, the trans- 

 formation is complete. In the interstratified sandstones, which 

 are sometimes conglomerate, masses of the same green mineral 

 are found ; and it was also observed filling fissures in fragments 

 of a bright red, and much indurated shale, which had fallen 

 from a high part of the chff. 



This green mineral is found by chemical analysis to be distinct 

 from serpentine, and is essentially a hydrous silicate of alumina, 

 protoxide of iron and potash, with small portions of soda, lime 

 and magnesia. Its greater density serves also to distinguish it 

 from sei'pentine. It occurs in schistose masses with a granular 

 texture, also botryoidal, with appearance of concentric structure, 

 and a conchoidal fracture. Hardness 2*5 to 3'0. Density of 

 the schistose specimens 2-68 to 2*71 ; of the botryoidal, 2'78. 

 Lustre waxy, shining ; streak white ; powder unctuous ; colour 

 greenish -white, yellowish -green, olive- green, often mottled; 

 translucent, subtranslucent. Very fragile, especially when moist- 

 ened; sectile; the light-colom-ed portions resemble in appear- 

 ance some specimens of indurated talc. 



To distinguish this material, and to recall its resemblance to 

 ophite or serpentine, I provisionally gave it the name of par- 

 ophite, without, however, claiming for an amorphous product of 

 the alteration of a sedimentary rock the rank of a distinct mineral 

 species. I give in connexion with some analyses of this sub- 

 stance, one of the unaltered schist, which passes in a little distance 

 into parophitc. The colour of the schist is dark ash-gray, some- 

 times marked with red ; the laminae are somewhat curved, their 



