366 ME. A. M. FINLAYSON ON THE NEPHRITE [Aug. I9O9, 



■chemical constituents. Many of the antigorites, however, which 

 were examined in the course of this work appear to he due to 

 pressure-effects on fibrous serpentines, rather than to derivation 

 from pyroxenes [21, p. 166]. 



Shallower conditions of metamorphism have doubtless been 

 responsible for the production of bastite and of talc from pyroxene, 

 and of some of the serpentine. A considerable amount of talc 

 may have been produced from pyroxenes, by those hydrothermal 

 processes which are believed to have effected or initiated much of 

 the serpentinization of olivine. 



(7) Structural significance. — The magnesian rocks which 

 have been described constitute a belt parallel to the strike of the 

 older sedimentaries, parallel to the granitic belt of the Alps, and 

 parallel to the structural axis of the Alps and to the trend of the 

 island. This combination of circumstances seems to indicate a 

 line in the earth's crust along which dynamic forces have been 

 concentrated. The recent volcanic zone of the Pacific, extending 

 from the central volcanic district of the North Island, through 

 Tofua and Savaii, to Honolulu [28], is parallel to this, although 

 not in alignment with it ; while the Tertiary volcanic rocks of the 

 southern islands, of Dunedin, and of Banks's Peninsula also lie on 

 another parallel line. To pursue the subject further would lead to 

 idle speculation, and serve no useful purpose ; but enough has been 

 said to show that the magnesian belt is one of the indicators and, 

 so far as we can judge, one of the effects of the Pacific trend-lines 

 to which Mew Zealand owes its geographical position. 



III. New Zealand Nephrite. 



The occurrence of this mineral was first made known by George 

 Porster [1] in 1777, and described by P. von Hochstetter [2] in 

 1864. Since then it has been described in more detail by MM. 

 Duparc & Mrazec [3], Dr. Berwerth [4], and Dr. Dieseldorff [5]. 

 In addition to this, references to and analyses of the mineral will 

 be found in works by Fellenberg [6], Pischer [7], Damour [8], 

 Allen [9], Arzruni [10], Clarke & Merrill [11], and others. Lastly, 

 the recent elaborate investigations conducted by American peno- 

 logists and chemists on the Heber P. Bishop collection of jades [12] 

 contain descriptions and analyses of New Zealand specimens. All 

 the work hitherto done, however, has suffered from the want of 

 knowledge concerning the mode of occurrence of the nephrite, and 

 from the fact that none of the investigators were able to collect 

 their material in the field. 



The associations of nephrite or ' greenstone ' with Maori life 

 and lore have been carefully investigated by Mr. (now Judge) 

 Chapman [13]. 



