Copper-Tin N'eins o£ the Akénobé District. 23 



of calcite, sometimes admixed with cryptocrystalline hydroxide of 

 iron, are scattered through the rock. The garnet is a very 

 characteristic component and is sometimes abundantly scattered 

 through the rock. It varies from a microscopic size to 3 mm., 

 rarely up to 5 mm., in diameter, and is well crystalhzed in 

 202. or 202, oo 0. It is isotropic and irregularly cracked, and 

 flesh-coloured in thin section. Inclusions of apatite needles, often 

 attaining a length of 1 mm., are very common in garnet. The 

 apatite i^ found also in the groundmass. 



Felsite. A dull-lustered, compact and lithoiditic, white or gray- 

 coloured rock is exposed, as a dyke through the green slates, along 

 the road-cutting between the Meisoi and Daidô mines, on the 

 western side of the Akénobé River. It is about 3 meters tliick, 

 and strikes N. 20° E. and dips toward N. W. at an angle of 80°. 

 ' Under the microscope, it shows a microgranular structure 

 consisting of xenomorphic grains of quartz and feldspar. While 

 quartz remains fresh, feldspar is altered to kaolin admixed with 

 more or less sericite in fibers and scales. No ferromagnesiaa 

 minerals are recognizable, but here and there are scattered clusters 

 of grains of brown iron ore. No phenocrysts are present. 



Felsite- Porphyry. A lithoiditic rock, similar to that described 

 above but evidently wdth some megascopic phenocrysts of feldspar, 

 occurs in the adit of Mannenko as a dyke across the vein. It 

 strikes N. 60° E. and dips toward S. E. very steeply. Its thickness 

 is 2 meters or more. 



Under the microscope, the groundmass is similar in composition. 

 and structure to the felsite described above. It is in places intensely 

 stained with clusters of grains of secondary brown iron ore. 

 Feldspar phenocrysts are usually intensely kaolinized, and some- 



