BY D. MAWSON. 



467 



American classification : — 



Norm. 



99-92 



Class iii., salfemane. 



Order 5, perfelic, Gallare. 



Rang 4, docalcic, Aiiverc/nase. 



Subrang 3, presodic, Auvergnose. 



Salfemphyro-pilotaxiti-auvergnose. 



Addend a. — This rock has been derived from the same 

 magma as has the Mau basalt, the difference lying in that it is 

 the habitant of narrower intrusions, which has had the effect of 

 breaking up the large glomerules. In character it is slightly 

 more basic and shows evidence of more rapid crystallisation. 

 Where there is an intrusive contact with the coralliferous lime- 

 stone of the older terraces, a marginal zone about one foot wide 

 appears, which, owing to the presence of very numerous white 

 particles, presents a speckled appearance. Under the microscope 

 these white particles are found to be irregular fragments of the 

 limestone, averaging 1 mm. diameter; very little resorption is 

 evidenced, and no new minerals have been developed, though the 

 limestone has lost all trace of organic structure and has assumed 

 the characters of marble. 



9. Uralite Porphyry. 



Locality . — Specimens were collected on Malekula as rolled 

 pebbles in the bed of the river entering the sea just to the north 

 of Atchin. The material represents various stages in the 

 metachemisation. 



