JULIEN, DETERMINATION OF MINERAL CONSTITUTION 135 



" ThermophyUite." 



From Hopansuo, Finland. Average of three analyses by Arppe, Hermann 

 and Northcote, with the formulas: (RO. SRPg) 2Si03 + 2HO and (MgO. 

 HO) + MgO. SiOg. 



" Oeladonite." 



An apple-green mineral, insoluble in acids, from Scotland. Average of 

 four analyses by Heddle. 



It is stated: "Com|). — A silicate of iron, magnesium and potassium, 

 formula doubtful" (Dana). 



" Houghite." 



From Rossie, New York. Analysis by S. W. Johnson. "A hydrotal- 

 eite derived from the alteration of spinel" (Dana). 



This was originally considered to consist essentially of variable mixtures 

 of SHjO. AI2O3 and MgO. HgO (Kenngott). 



