Geology and Mineralogy. 187 



came from a point not far distant. The sillimanite rocks have 

 been found in certain parts of Ceylon somewhat abundantly in 

 the garnetiferous leptynites. The author remarks : " The silli- 

 manite-bearing rocks have a strong resemblance to the khonda- 

 lites of Southern India ; they do not, however, occur in the same 

 way above the charnockite series, but completely incorporated 

 with it, forming probably bands and lenticular masses ; the rocks 

 have, however, been rarely seen in situ, and it has not been possi- 

 ble to study closely their relation to the charnockites proper. It 

 must be pointed out that there is a complete transition to the 

 ordinary granulite type. On the one hand, we have a rock com- 

 posed wholly of sillimanite, and all varieties from this, through 

 quartz-feldspar-sillimanite-garnet schist, to garnetiferous leptynite 

 with very little sillimanite, and ordinary garnetiferous and non- 

 garnetiferous leptynites can be collected." 



Intrusive granite rocks which have been called the " Balangoda 

 group " have afforded a number of rare and interesting minerals, 

 including, thorianite, thorite, allanite, baddeleyite, geikielite and 

 cassiterite. The thorianite occurs in moderate quantities near 

 Kondrugala in Bambarabotuwa, Sabaragamuwa. It is found in 

 heavy black crystals, more or less water- worn, associated with 

 zircon and pebbles of ilmenite. It is obtained by the same 

 method used in washing gems, and it is stated that the whole 

 amount thus far removed from Bambarabotuwa is less than 30 

 cwt., and it is not probable that more than a total of 5 tons could 

 be obtained from the Kuda Pandi-oya valley; two other localities 

 mentioned might yield half a ton additional. 



An interesting account is given of the occurrence of gems and 

 the methods of gemming in Ceylon ; this is supplemented by 

 some . excellent illustrations reproduced from photographs. The 

 gem-bearing gravel, or illam, occurs in beds, patches, or pockets 

 deposited by streams and rivers, and may be found at any depth, 

 up to 120 feet, the greatest depth observed, viz : at Botiyatenna, 

 Rakwana. Where the illam is found in its typical form, it con- 

 sists largely of white quartz pebbles, ranging in size from a small 

 shot to a football, indeed in all gradations of size up to that of 

 the bowlders associated with the illam. 



21. The Production of Precious Stones in 190 Jf ; by George F. 

 Kunz (Extract from Mineral Resources of the United States, 

 U. S. Geol. Survey). — The annual reports in regard to the Pro- 

 duction of Precious Stones always contain matter of interest. Of 

 recent discoveries in this country the most important noted are 

 those of Southern California, particularly in San Diego county, 

 which has yielded near Ramona fine blue and white topaz ; also 

 rose-colored beryl at Mesa Grande and Pala, and axinite at Bon- 

 sall. The colored tourmalines, both in California and Maine, have 

 been mined extensively, and the new locality of peridot at Talklai, 

 Gila Co., Arizona, has yielded large quantities of fine gems. 

 Much interesting information is given in regard to the diamond 

 industry, particularly in South Africa. 



