SOME OCCUREENCES OP PIEDMONTITE IN JAPAN. 311 



entirely free from any such, a fact which shows that the latter (Pied- 

 montite) has crystallized out before the yellowish-green Epidote. 



Garnet. 



In the Glaucophane-schist from Otakisan, in the Island of Sihoku, 

 we find a large number of rhombic dodecahedra (the size of peas) of a 

 greenish -yellow Garnet. Under the microscope, a slide of it appears 

 as made up of different minerals as shown in the figure (Fig. VIII). 

 This crystal is, indeed, a small mineral- cabinet of all that are found 

 in this rock except Glaucophane. The violet Piedmontite-needles, 

 clumps of dark Iron-glance, hexagonal scales of Iron-glance, the 

 knee-shaped twins of Rutile-needles and, lastly, highly vitreous grains 

 of Quartz, are all thrown together within the crystal, assuming more 

 or less a curved structure. These admixtures are supplemented and 

 completed by a Garnet substance. The colour of the Garnet itself is 

 deep yellow, and its crystal shows an optical anomaly, its behaviour 

 being just like an anisotropic mineral, caused probably by the strain 

 resulting from the interposition of the other minerals. Prof. Bonny(') 

 has also discovered Garnet in a Glaucophane-bearing rock near Berrioz 

 in the Yal d'Aoste, in theAlps. Here the Garnet sometimes contains 

 Glaucophane and dark dust, which he suggests to be possible in 

 certain cases of subsequent infiltration. Our Garnet is entirely free 

 from the interposition of Glaucophane, althougli the rock itself is a 

 Glaucophane-schist; and the above-mentioned interpositions, i. e. Pied- 

 montite etc., seem to be formed prior to, or coteuiporaneous with the 

 formation of Garnet. It is a very /' remarkable ficfc that the brownish- 

 red Garnet seems to be absent in the Piedmontite- and the typical 

 Glaucophane-schist; wdiile it is common in the Amphibolite-zone. 



(i) ' Ou a Glaucophaue-eclogite from the Val cV Aoste.' Miu. Mag. Vol. VII, No, 32, p. 2. 188G. 



