On Metallic Minerals. 391 



freely ia muriatic acid and to form with sulphuric acid a 

 tji.icl^ I'unly deposit of a white colour and perfectly tasteless. 

 \ aut disposed to think, it au incrustation of magnesiaa 

 carbonate of lime^ a^d the curdy matter au artificial 

 gyp^unl. 



'Oic talcose scltist lies between the serpentine and granite, 

 which Uist mentioned rock rears it head in one perpendicular 

 scnvp above the others perhaps fifty feet. It is composed of 

 feUjKir and quartz, with occasionally, black schorl, but no 

 mica Such an aggregate is a frecjueut njeinber among those 

 rocks in this country wiiich are called granite. It has becu 

 called a granite here for want of a better name, but as its 

 constituents have been given, a name can lead to no 

 erroneous conclusions. It is very much to be wished that 

 geologists Mouhl oftcner condescend to give the consti- 

 tuents, &c. of the rocks they describe. In the difticult 

 science of geology, as yet in its infancy, conciseness is well 

 •acrificed for a detail which shall render its facts intelligible, 



1 have described marble as forming the right bank of the 

 river at and near the dam ; it does not do so, however, ex- 

 clu.sivcly, as talcose schist is also there, but in subordinate 

 quantity, and a short distance back from the shores granite 

 ih, 1 believe, as on the opposite side, also found. This 

 warble sooietimes s|)otted by serpentine, forming a verde 

 UHiicu, at others almost of a pure and brilliant white, forms 

 an extensive bed si^me distance below the Marble Falls, but 

 it i» near them that that beautiful variety, chectjuered by 

 serpentine has been found ; it also occurs in large nodules 

 imbedded in the limestone, and again one part of a mass is 

 wliitc marble— the other Ker[)entine. This serpentine is of 

 the purest kind, being of a very vivitl green colour and 

 very tran(>luccnt. The marble with which it is asHociated 



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