Reviews — Records of the Geological Survey of India. 127 



cannection with the later phase of igneous activity. They hold that 

 deposition, consequent on diminution of pressure and temperature, 

 was precluded in the case of fluorspar from taking place in the lower 

 parts of the vein-fissures, owing to the fact, pointed out to them by 

 Dr. W. Pollard, that superheated steam decomposes calcium fluoride. 

 The relatively low specific gravity of the mineral probably had some 

 further influence in determining the limitation of the mineral to the 

 upper parts of the fissures. The economic uses of fluorspar are discussed 

 from an historic and practical point of view, and the paper concludes 

 with a bibliography. 



III. — Geological Hand-Map of the Bkitish Isles. — Mr. Edward 

 Stanford, of 12, Long Acre, has sent us a copy of a neat colour-printed 

 map with the above title, which he has published at the price of 6rf. 

 The size of the sheet on which the map is printed is about 7| by 

 10 inches, and it should prove useful for handy reference in classes. 



IR E -V I E -^77" S- 



I. — Records or the Geological Sukvet or India : General Report 

 FOR 1907. By Sir T. H. Holland, K.C.I. E., D.Sc, F.R.S., 

 Director.^ 



rilHE Director observes in his introduction that there has been 

 J_ satisfactory progress in mineral production during 1907, and an 

 extraordinary increase in the activity of prospectors, " mainly inspired 

 by the phenomenal success of those who were already prepared to 

 meet the increased demand for manganese-ore and coal." The state- 

 ment of mineral concessions during the year is indeed most remarkable, 

 and the details of the 600 licences granted fill thirty-one pages of the 

 report. Clearly the prospectors are in an optimistic mood. 



The Director in his obituary notice calls attention to the value and 

 importance of Mr. Griesbach's work.- 



Mineralogy. — The jadeite deposits in Upper Burma have been 

 carefully investigated, and the recent conclusions, both as to the 

 origin and age of this mineral, differ materially from the views 

 formerly advanced.^ It was known previously that the jadeite 

 formed a light-coloured layer in the midst of a dark-green serpentine, 

 and it was conjectured that the jadeite must have separated as 

 a primary segregation from the magma. There seemed some difiiculty 

 in understanding how a soda-alumina silicate could have segregated 

 from a magnesian rock, but recent observations tend to show that the 

 jadeite occurs in a metamorphosed igneous dyke intruded into the 

 serpentine. It is concluded that the jadeite is the result of the 



1 [This review was written by our late friend and co-editor, Mr. W. H. Iludleston, 

 and sent to us on January 20, 1909, nine days before he passed away from his 

 active, useful life, -without any illness or suffering, happily engaged up to the last 

 moment (see Obituary). — H. W.] 



2 See Geol. Mag. for 1907, p. 240. 



3 Geol. Mag., 1907, p. 328. 



