feo far as can be ascertained, gyrolite was first observed 

 by K. L, GiESECKE in the year 1811. He gives the following 

 description of a mineral from Niakornat in the district of 

 Umanak, Greenland, which evidently refers to this species ^): 



«1st aber Mandelstein ein Gemengtheil dieses Conglomérats, 

 so sieht man in demselben Quarz, Chalcedon, faserigen Mesotyp 

 in Nieren von verschiedener Grösse. Der letztere geht oft ins 

 krummblätterige über, ist schiefrig, hat einen starken Perlen- 

 mutter-, oft beinahe metallischen (Silber-) Glanz, und braust 

 etwas mit Salpetersäure. Seine Krystallisation scheint die sechs- 

 seitige Tafel zu sein.» 



Gyrolite seems to be again indicated by Giesecke in 1814, 

 when, in describing the minerals of Disko, he writes^): 



«The Apophyllite also occurs in a radiated form similar 

 to stilbite, but with a more brilliant lustre, and presenting on 

 the surface a crystallisation similar to the cock's-comb barytes.» 



In this passage the relationship with apophyllite is clearly 

 recognized; but later writers confounded the mineral with me- 

 sole (thomsonitel and even with the radiated zeolites. Thus 

 Haidinger writing in 1827'^) describes eight specimens of 

 "Mesole" from Allan's collection (now in the British Museum, 

 London), and remarks that "these varieties show a very great 



^) Giesecke, Mineralogiske Rejse i Grønland, Copenhagen, 1878, p. 245. 

 2) Giesecke, On the minerals of Disko Island, Trans. Roy. Soc. Edin., 



IX, 1816, p. 271. 

 ^) Edinbourgh Journal of Science, VII, p. 19. 

 XXXIV. 7 



