104 B. KOTO 



the smaller the felspar-grains are, the more interpositions they 

 contain, becoming finally extremely dull so that the felspar- portion 

 is no longer visible, thereby presenting an aspect quite similar to that 

 of a zoicitized felspar of the so-called sanssurite-gabbro. 



A minuter inspection under high powers resolves the cjuasi- 

 zoicite into a monoclinic epidote. It is found as microliths and 

 round crystalloids. Of the various forms, some have a rhombic out- 

 line, or are needle-shaped ; while others are developed in unsymmetrical 

 wings with a twinning-suture at the middle as is seen mßg. 11. PI. II., 

 The optical investigation of them is made impossible by the inter- 

 ference of the other grains and the enclosing felspars. There are seen 

 frequently actinolite-prisms whose basal sections often met with in 

 slides are of an acute rhombic outline without any trace of the 

 clinopinacoid as is usually supposed to be the case ; consequently the 

 prism shows dark longitudinal margins on account of its high refracting 

 power — and the terminations are round and often broken. Rhombic 

 dodecahedra of garnet together with pleochroic, yellowish-green 

 pistacite columns Q/o-^/i centim.) lie also imbedded in the felspars. 



The general mass of the rock consists of a grass-green, lamellar- 

 fibrous substance which encircles the porphyritic felspar-grains. 

 This green substance is slightly pleochroic showing a deeper shade of 

 colour when the chief section of nicol is at right angles to the axis 

 of the fibres, and remaining dark between crossed niçois. It transmits 

 only a foint l)liie light. In a hot solution of hydrochloric acid, the 

 greater part of this green substance is removed from the slides, and 

 tlie remaining pc^rtion becomes almost colourless — it is chlorite. 



The minerals found as interjiositions in the felspar-nodules occur 

 here again in the fjronmlma^s., and the green scaly-lamellar mass 

 is interlarded throughout by epidote-needles and grains, and especially 

 actinolite-prisms which are like spicules in the spongy mass. 



