Gold-quartz Deposits of Pahang. 75 



systems of the Upper and Lower Peninsulas of Michigan, the author 

 describes the mechanically and chemically formed Azoic rocks, and 

 those produced by igneous agency, adding a table which shows his 

 scheme of classification of rocks, and explaining it. 



The divisions of the Azoic system are then described in order, 

 beginning with the oldest — the Cascade Formation, which consists 

 of gneissose granites or gneisses, basic eruptives and schists, 

 jaspilites and associated iron ores, and granites. 



The rocks of the succeeding Eepublic formation are given as 

 nearly as possible in the order of their ages, commencing with the 

 oldest : — Conglomerate, breccia and conglomeratic schist, quartzite, 

 dolomite, jaspilite and associated iron ores, argillite and schist, 

 granite and felsite, diabase, diorite and porodite, and porphyrite. 

 The author gives a full account of the character, composition, and 

 mode of occurrence of jaspilite, and discusses the origin of this rock 

 and its associated ores, which he at one time considered eruptive ; 

 but new evidence discovered by the State Survey and the United 

 States Survey leads him to believe that he will have to abandon 

 that view entirely. 



In the newest Azoic formation, the Holyoke formation, the 

 following rocks are met with : — Conglomerate, breccia and con- 

 glomeratic schist, quartzite, dolomite, argillite, greywacke and 

 schist, granite and felsite (?), diabase, diorite, porodite, peridotite, 

 serpentine, and melaphyre or picrite The conglomerates of the 

 Holyoke formation contain numerous pebbles of the jaspilites of the 

 underlying Eepublic formation ; a description of the Holyoke rocks 

 is given, and special points in connexion with them are discussed. 



The author next treats of the chemical deposits of the Azoic 

 system, gives a provisional scheme of classification of ores, and 

 discusses the origin of ore deposits. 



The rocks of the Palaeozoic system are next described, and it is 

 maintained that the eastern sandstone of Lower Silurian age 

 underlies the copper-bearing or Keweenawan rocks. The veins and 

 copper deposits are described in detail, and the paper concludes 

 with some miscellaneous analyses and descriptions, as well as a list 

 of minerals found in Michigan. 



2. " The Gold-quartz Deposits of Pahang (Malay Peninsula)." 

 By H. M. Becher, Esq., P.G.S. 



The gold-quartz deposits of Pahang traverse an extensive series 

 of slates, sandstones, and dark-coloured limestones, sometimes more 

 or less metamorphosed, and probably of Palaeozoic age, occupying 

 the low-lying hill-country on the eastern side of the central granitic 

 mountain-range. The prevailing dip of the strata is eastward. 



In some places the auriferous rock penetrates adjacent intrusive 

 syenites, but has not been traced in connexion with the main granitic 

 'massif which is generally considered to be the matrix of the 

 cassiterite found in the ' Straits ' alluvial Tin-fields. 



The gold occurs in lodes and irregular formations, which, how- 

 ever, are not distinguished from one another by any hard-and-fast 



