107 



ception is the mineral from Niakornat, wich possesses so 

 many particular properties that it may, perhaps, be somewhat 

 doubtful if it in reality belongs to gyrolite. In the following 

 remarks I shall point out the resemblances and the differences 

 between the gyrolite from Niakornat and other gyrolites. 



The occurrence is very uniform and characteristic. The 

 mineral is always found in cavities in basalt or basaltic tufa; 

 the first formed minerals associated with it in these cavities is 

 for the Greenland localities one of the zeolites natrolite, meso- 

 lite, scolecite or thomsonite and in some cases saponite alone 

 or together with one of the named zeolites; the last formed 

 mineral ist mostly apophyllite and in a few cases calcite 

 or quarz. 



For the Scottish gyrolites Cdrrie has given me the following 

 scheme where is collected all what is known about the mineral 

 associations ^): 



1. Faroelite-Scolecite-Gyrolite (Treshnish Islands). 



2. Mesolite-Gyrolite ( — — ). 



3. Mesolile-Gyrolite-Apophyllite ( — — ). 



4. Faroelite-Gyrolite ( — — ). 



5. Mesolite-Gyrolite-Apophyllite iRudha na h'Airde Glaise, 



Portree, Skye). 



6. Mesolite-Gyrolite ( — — — ). 



7. Faroelite-Gyrolite ( — — — ). 



8. Gyrolite-Apophyllite (Quiraing, Slorr, Skye). 



9. Faroelite-Gyrolite I — — — ). 



10. Faroelite-Mesolite-Gyrolite ( — — — ). 



11. Scolecite (?)-Gyrolite (Rud h a nan С lach, Skye). 



12. Mesolite(?)-Gyrolite (Sunday, Canna). 



13. Mesolite(?)-Analcime-GyroIite (Sgeir De arg. Mull). 



14. Gvrolite-Xonotlite (Gribun, Mull). 



1—4, Heddle: Min. Mag. 8, p. 130; 5 — 6, Hedhle: Trans. Geol. Soc. 

 Edinb. 7, 1899, p. 331 ; 7—13, Curute (private information); 14, Heddle: 

 Min. Mag. 5, 1882, p. 4. 



