108 Lieut. Baddeley on Suljjhutc of Strontiati, cj-c. 



there appears to have taken place an exchange of minerals along the 

 frontier, the quartz having entered into the limestone as a hostage 

 for the lime in the granite. Capt. Bonnycastle has observed that in 

 these cases it is always the quartz which is foremost ; like the light 

 infantry of an army previously to a general engagement, while the 

 felspar, which is the main body is in allignment or column in rear. 

 He also considers the fact to be corroborative of an opinion expressed 

 by Humboldt in his Geognosy, viz. that there appears to be no reci- 

 procity or sympathy in nature between limestone and felspar. I 

 have not used the language of either of these gentlemen, but I be- 

 lieve the sense is the same. 



The felspar, which is usually the predominating mineral in this 

 aggregate, is generally of a deep flesh-color; and when this is joined, 

 as it often is, to opalescent quartz, a beautiful compound is the re- 

 sult. The structure of the rock, when the felspar is the predomi- 

 nating mineral, is either compact or laminar : when hornblende 

 abounds, it is generally foUated like gneiss, and sometimes porphy- 

 ritic. It exhibits no distinct appearance of stratification, although I 

 have sometimes imagined that such a feature did exist, and that ver- 

 tical strata directed between south and south-west, could be obscure- 

 ly traced. Schorl, epidote, and tremolite, are among the dissem- 

 inated minerals. The schorl is usually in small imperfect crystals, 

 studding the surface of the natural joints of the syenite or granite, 

 while the epidote occupies a similar position in the greenstone ; the 

 former is also found in tolerably large pieces, (much intermixed 

 with white quartz) imbedded in the granite. These pieces shew 

 very little tendency to regular crystallization, but the shining coal- 

 black faces of prisms, deeply striated, may often be seen. Although 

 felspar usually envelops the schorl, it is seldom intermixed with it. 

 A curious bed, composed almost entirely of epidote and tremolite, 

 is met with in this neighborhood, holding a geological position which 

 implies a contemporaneous origin with the crystalline rock above de- 

 scribed. This bed, together with the frequent occurrence of schorl 

 and epidote in this rock, affords the best support to its pretensions to 

 be considered primary. The following is a mineralogical descrip- 

 tion of the bed in question, with which I shall terminate this paper. 



This aggregate strongly resembles a verde antico, or a mixture 

 of granular serpentine and white limestone ; its colors are therefore 

 green (dark) and white. The white mineral is the paste through 

 which the other is distributed, usually in small rounded grains, 

 though an aggregation of prismatic ciystals or of laminae may be oc- 



