Metamorphic Conglomerate in the Green Mountains. 273 



that afterwards were built into the ottrelite with total disre- 

 gard to any observed relationship, in the same manner that 

 quartz and feldspar droplets were built into albites in another 

 phase of this rock. Other inclusions are graphite (determined 

 by deflagration) and little coffee-brown llmenite plates (titan- 

 eisenglimmer). A powerful current from an electromagnet 

 applied to the rock powdered and run through a 120-mesh 

 sieve failed to attract but little, so that magnetite and prob- 

 ably ferrous oxide are absent. The usual test for titanium 

 gave a positive reaction. 



As in biotite and chlorite, pleochroic zones about crystals of 

 zircon are very common in the ottrelite and the characteristic 

 dependence of maximum pleochroism upon maximum pleo- 

 chroism of enclosing mineral is observable. While zircon 

 usually occupies the centers of these zones, others occur, hav- 

 ing no perceptible associated inclusion, but are circular areas of a 

 brownish color, not resolvable with the highest power, that are 

 probably rutile grains. 



Ottrelite schist showing formation of ottrelite at many different points. Each 

 small area is oriented with all the others, forming a large area having a general 

 prismatic outline. The prism (A) has been developed transverse to the schistosity of 

 the rock. The background (B) is largely gueissic quartz with some secondary feld- 

 spar, x 25. 



Although twinning with composition face parallel to O is 

 not uncommon in the ottrelite a large part of what seems to 

 be twinning is seen to be due to overlapping plates. As the 

 stage is revolved the wavy extinction caused by this may be 

 observed, — the usual spherulitic structure. Examples of 

 crystal growth set up in several places at the same time occur 



