lU 



Appendix. 



After the above paper was written I received from Cornu ^) 

 a very interesting treatise upon gyrolite and related minerals. 

 According to this the mineral from Niakornat is a new 

 mineral species and it is named reijerite and besides the dif- 

 ferences between it and gyrolite, which 1 had already found, 

 there is also slated to be a small difference in respect to the 

 index of refraction, the со of the gyrolite being determined at 

 1'54 — 1'55 while for the reyerite it is 1'5645. The reyerite is, 

 stated to originate from Disco as well as from Niakornat; 

 it may, however, be the same locality as Niakornat was 

 formerly described as a locality upon Disco, as we have seen 

 above. As the paper by Cornu is stated to be a preliminary 

 one a more exact description of the specimens will, perhaps, 

 clear up this point. 



As Greenland localities for gyrolite there are named: 



1. Korosoak (= Kororsuak near Godhavn): from 

 that place I have found no gyrolite ; Cornd describes three 

 different varieties all occurring together with apophyllite partly 

 older and partly younger than that mineral. 



2. Kara tut near Godhavn {= Karartut, see above 

 p. 105) here the gyrolite is described as implanted upon apo- 

 phyllite, while, on the specimen examined by me it is distinctly 

 older than that mineral; the form described as small spheres, 

 also shows that the specimens are quite different from each other. 



3. Niakornak. From that locality I have found no 

 gyrolite besides the above named which by Cornd has been 

 termed reyerite. 



M Tschermaks min. u. petr. MUth. 25, 1907, Heft 6. 



