286 Correspondence — John W. Evans. 



The nephrite, or Pounamu of the Maori, occurs as nodules and 

 veins in the serpentine-carbonate and talc-carbonate rocks of the Griffin 

 Range, Westland. Its commonest colour is a deep translucent green, 

 but many different shades occur, depending on the percentage of ferrous 

 silicate, on the presence or absence of flaws and cracks, and on included 

 or infiltrated oxides of iron. Some of the dark-green nephrites are 

 among the finest specimens of this mineral in existence. A pale 

 whitish-green variety is also occasionally found. It is, however, 

 rather opaque and never approaches in sheen the famous pale * jades ' 

 of Turkestan. 



Microscopically, the nephrite shows a foliated or confused aggregate 

 of very fine fibres, the denseness of the fibrous mass being evidently 

 the cause of its hardness. 



It appears to have been originally formed by several modes : ( 1 ) by 

 contact-action between peridotites and lime-bearing rocks, (2) by 

 uralitization of pyroxenes, (3) by direct transformation of olivine 

 into finely fibrous amphibole, (4) by deep-seated metamorphism of 

 serpentine -talc-carbonate rock or its prototype. 



These modes all suffice to produce the necessary chemical changes, 

 but the transformation to true nephrite has involved, in addition, 

 intense rock-pressure and movement. Thus has finally resulted the 

 dense foliated or felted aggregate of fibres which characterizes nephrite. 



coRi^EisiE'oisriDEnsroE. 



CHEYSOLITE, CHRYSOTILE, AND KARYSTIOLITE. 



SiK, — May I call the attention of your readers to the inconvenience 

 caused by the similarity between the terms chrysolite, a synonym of 

 olivine adopted by Dana as the name of the species, and chrysotile, 

 given by Kobell (Jahrb. prakt. Chem., 1843, vol. xxx, p. 469) to the 

 fibrous variety of serpentine. Twice within the last twelve months 

 I have had occasion to use the term ' chrysotile ' in publications 

 (Proc. Geol. Assoc, 1908, vol. xx, p. 462 ; Bull. Imp. Inst., 1908, 

 vol. vi, p. 394), and on both occasions it has been transformed into 

 ' chrj^solite ' . In the case of the article in the Bulletin I was able to 

 verify the fact that the right word appeared not only in the manuscript 

 but in three successive proofs, and that it was only at the last moment 

 that it was corrected (!) in eveiy place where it occurred by a reader 

 for the press. In the other case the proofs were not available for 

 reference, but the manuscript was found to be correct. 



The two words are a continual source of confusion to students, and 

 I would suggest the revival in the form harystioUte of the original 

 name of the mineral, Kcipv^TWi \tOo9, from Karystos, in Euboea, where 

 it was obtained (\lin. Mag., 1906, vol. xiv, pp. 143-5). ' Karistia' was 

 still in use in modern Greek in this sense towards the close of the 

 eighteenth century (id., p. 147). The term ' marmor carystium ' 

 appears to have been applied by Pliny to serpentine rock quarried in 

 the same locality (Nat. Hist., iv, 21, and xxxvi, 7). 



John W. Evans. 



Imperial Institute. 



April 30, 1909. 



