450 Transactions. — Geology. 



Eep., 1870-71, p. 5), is probably a misprint, no such mineral, as far as I am 

 aware, being known. He also, page 148 of the same volume, without descrip- 

 tion, mentions the occurrence of " oxide of silver, and probably sulphate ol 

 silver," from the new Golden Crown Claim, but as neither of these minerals 

 are mentioned in Dana's mineralogy, I am unable to say to what he refers. 



Meecuey. 



This metal has been found in New Zealand, both in the native state and 

 also as Cinnabar, but only so far in small quantities. 



Native Mercury, Hg, occurs at Waipori, in the district of Otago, where 

 it is found in the alluvial wash of the district as small globules, and also 

 alloyed with gold to form amalgam (Hector, Jurors' Eep., p. 404). Native 

 mercury also occurs at the Ohaeawai Springs, near the Bay of Islands, but 

 only in small quantities. It has been known since 1866, and in 1870 Captain 

 Hutton described a visit to the locahty (Trans. N.Z. Inst., vol. iii., p. 252), 

 and the mode of occurrence has since been described by Dr. Hector (Geol. 

 Eep., 1874-76, p. 5), as follows : — " The Ohaeawai Springs deposit a brown 

 sandstone, which forms laminated beds 10 feet to 15 feet in thickness. This 

 sand, which is an incoherent granular siliceous deposit, includes fragments 

 of the surrounding vegetation, and thin layers of Cinnabar sand and globules 

 of Metallic Mercury. The layer of sandstone containing mercury is only 4 

 inches thick, and is confined to a very limited area, and the attempts made 

 to collect the mercury have not, hitherto, been profitable." 



Cinnabar, Hg'. — This mineral occurs as rounded grains in the alluvial 

 deposits of the Obelisk Eanges, Potter's Gully, Dunstan, Serpentine Valley, 

 and Waipori, in Otago (Hector, Jurors' Eep., pp. 264, 436), and also in the 

 deposits of the Ohaeawai Springs previously mentioned. 



Aet. LXXIII.— Ow Crystalline Rocks. By W. D. Campbell, F.G.S. 

 [Read before the Auckland Institute, 11th July, 1881.] 

 Ceystalline rocks occur as altered sedimentary deposits, and comprise most 

 of the eruptive rocks ; the latter are to a great extent crystalline at the time 

 of their formation, while the former were originally loose accumulations of 

 various iDarticles for the most part. Both kind3 of rocks are subject to 

 changes of condition which are termed metamorphism, by which the 

 internal texture and composition have been altered gradually by chemical, 

 electric and crystallograpbic action, by the withdrawal of, or addition, or 

 substitution for some of the chemical elements, aided by heat and watery 

 vapour acting under intense pressure. The changes in the sedimentary 

 rocks are usually more apparent than in the eruptive, so that the term 

 metamorphism has been more especially applied to these rocks. 



