36 Reviews — Ore Deposits of Environs of Hanano-Yama. 



often of very coarse texture, and containing some very remarkable 

 masses of sky-blue calcite. The origin of this peculiar colour is 

 unknown. The upper part of the limestone was apparently more 

 dolomitic, and here brucite has been largely developed, often in 

 association with graphite. In the contact zones, where diffusion of 

 silica has taken place from the magma, the commonest minerals are 

 wollastonite, vesuvianite, and garnet, with diopside and monticellite. 

 Some supposed new minerals are described under the names of 

 wilkeite, I'iversideite, and crestmorite ; the analyses and description 

 of these are not very convincing, and suggest mechanical mixtures of 

 silicates and phosphates. In close association witli the igneous rocks 

 are also found axinite, scapolite, and datolite, which belong properly 

 to pneumatolytic metamorphism. The chief interest of this remark- 

 able occurrence lies in the fact that it seems to combine in itself 

 nearly all the types of limestone metamorphism hitherto described. 

 No indication is given of the age of the limestone or of the 

 intrusions. 



E. H. R. 



XI.^The Ob,e Deposits iisr the Environs op ITanano-Yama, near 

 THE Town ov Oda, Province of Nagato, Japan. By Takeo 

 Kato. Journal of the Meiji College of Technology, vol. i, 

 pp. 1-95, with 10 plates, 1916. 



FROil an exhaustive study of the mining district of Oda, in the 

 Province of Nagato, Japan, a district which has long attracted 

 the interest of geologists and mineralogists because of the existence 

 of contact-metamorphic ore deposits of diverse character and the 

 occurrence of beautiful specimens of copper minerals — cuprite, native 

 copper, malachite, and chrysocolla — and of various sulphides, silicates, 

 and other contact minerals. Professor Kato draws some important 

 conclusions with regard to certain of the problems confronting 

 students of contact metamorphism. He considers that "iron, silica, 

 various rarer metals, mineralizers, etc., i.e. the greater part of the 

 elements composing the lime-silicate minerals and the entirety of 

 ore-minerals of the contact metamorphic deposits, have been derived 

 from the emanations from the magma". 



Another important point is that the metamorphosing solutions first 

 expelled from a consolidating acidic magma are siliceous in character, 

 and are afterwards basic, becoming rich in iron, copper, and other 

 metals, while still containing some silica; finally, at the end of the 

 mineralization the solutions are rich in iron, copper, and sulphur, 

 but contain little silica. The lime-silicates are therefore formed 

 before the minerals rich in iron, and the sulphides and oxide-ores 

 appear about at the same time as the andradite and hedenbergite. 

 Although mineralization in contact metamorphic deposits begins with 

 the magraatic intrusion and continues up to solidification of the entire 

 mass, the formation of the main deposits is confined to the early — the 

 pneumatolytic and pneumato-hydatogenetic — stages, while subse- 

 quently occur the hydrothermal alterations of the country rock and 

 deposition of sulphide ores associated with quartz and calcite, but no 

 lime-silicates. The paper is well illustrated. 



