THE ARCHAEAN FORMATIOX OF THE ABUKUMA PLATEAU. 255 



think the present augite rrpre.fipntfi in the non-aluminous group an incipient 

 stage of iiw formation of the so-called pseado-lujpersthene of an aluminous 

 augite. 



Sometimes grains witli the aug-ite-cleavage are observed (Fig. 12, 

 a, &, and c), and these basal sections are marked witli numerous spots 

 which are nothing but the cross-cut of the cyhndrical lioles, well seen on 

 the longitudinal sections (d and c) of the mineral. There seems, how- 

 ever, no regularity in the arrangement of these dots. The pleochroism 

 is faintly observed only on the cliuopinacoid, when the interior portion 

 is of a darker shade than the peri])hery ; and the absorption is 

 the strongest when the principal axis coincides with the principal section 

 of the lower nicol. Some grains show intense polarization-colours 

 between crossed niçois, nearly equal to those of augite or olivine, 

 and these, when closely examined, always extinguish light in oblique 

 directions with reference to a few cleavage-traces. The grains with 

 straight extinction are on the contrary very dull, -ranging fr<^m grey 

 to light-brown. 



The augite is scattered through the entire mass, to the ex- 

 tent of nearly the half, and when it occurs associated with a rather 

 green hornblende which is present only in small quantities, it is 

 imbedded within the sul^stance of the hornblende (Tig. 3, PI. 

 XXIIl), each having different optic orientations, as shown in the figure. 



From the whole habitus I consider these light-green grains to be 

 the salite of Prof. Kalkowsky, wIkj was the first to point out the wide 

 distribution of this mineral in amphibole-schists. unfortunately his 

 original paper is not accessible to me, and a strict comparison of the 

 salite from the Oberpfälzer Waldgebirge with the Japanese mineral is at 

 present a matter of impossibility. Prof. Pecke' has also given a 



1 Die Gneisaformatioii des nieckrösterreichischen Waldvierteh. Tschermak's mineralog. und 

 petrogr. Mitth. Bd. IV, p. 189. 



