I 04 



pi:ntti eskola. 



M.-N. Kl. 



Garnet-amphibolite from Kantalahti, Kola Peninsula. 



Ill the sontlivvcstcni |);iil of tlic KcA^i Peninsula, around and west of 

 Kantalahti l)ay, there occurs garnet-amphil)olitc on a x'cry extensiye area, 

 forming a zone which probably continues hundreds of kilometers towards 

 the Northwest'. This rock was first mentioned by A. Stelzner- and called 

 an eclogitc-likc rock. Later on W. Kamsay gave "a note of it"^. To this 

 same formation probably belong those rocks b\- E. v, Fedoroff described 

 as drusites'^ and assumed to be a kind of igneous rocks. 



A specimen of this rock, collected by professor W. Ramsay in 1890 

 and ke[it at the collection of the Mineralogical institute of the university 

 ol Helsingfors, was subjected to quantitative investigation by the writer. 

 This rock was chosen in part because it seemed desirable to ascertain 

 the composition of a rock type that has such an extensive occurrence, but 

 more because I thought that this garnet-amphibolite might possibly be an 

 amphibolitized eclogite. 



The garnet in this rock, being filled up with minute inclusions of 

 quartz, was very difficult to separate in pure form, and only after a 

 threefold treatment with Clerici's solution alternating with crushing to a 

 finer and finer grain was I« finally successful in securing a practically clean 

 material. I executed the analvsis with the following- result: 



SiO. 



38.89 



648 



648 



206 



614 



100.41 



Sp-g- = 3-965 <t=- 12°). 



"d = 1-7889. 



RO : R.,03 : SiO., = 2.98 : i : 3.15. 



Composition (F"e5-MniMg^(jCa3.3)3(Alg^Feg)2. 



' ^'- J- J- Sedcrholm's Geological Map of Fennoscandia in Bull. Comm. gëol Fini. N:o 24, 

 1910. 



2 Bemerkungen über krystallinische Schiefergesteine aus Lappland. N. J. Min. 1886, II, 

 p. 102. 



3 \V. Ramsa\', Fennia 15, IV, 1890. 



■* According to what several Russian geologists have told me. Fedoroff's original papers 

 dealing with this subject have not been available to me. 



