152 
MR. C. BARRINGTON BROWN AND PROFESSOR J. W. JUDD 
read before this Society,* * * § the Count de Bournon correctly defined the crystallo¬ 
graphic characters of the species. Four years later the last-mentioned author laid 
before the Boyal Society his very valuable memoir, bearing the title, “ Description 
of the Corundum Stone and its Varieties, commonly known by the names of Oriental 
Ituby, Sapphire, &c., with Observations on some other Mineral Substances.”t In 
this work the mode of occurrence of corundum is discussed, and an admirable 
account is given of the minerals with which it is associated in the famous gem- 
yielding localities of Ceylon, China, and Southern India. In all of these districts 
de Bournon showed that the corundum occurs in crystalline schists ; being 
associated in the Salem district of the Madras Presidency with moonstone, anorthite, 
fibrolite, diaspore, hornblende, quartz, mica, talc, garnet, zircon, and magnetite; 
while in Ceylon its chief associates are spinel, pyrrhotite, tourmaline, ceylanite 
(pleonast), and zircon. De Bournon’s memoir is especially noteworthy as containing 
the first descriptions of two very important rock-forming minerals—anorthite 
( :£ indianite ”) and sillimanite (“ fibrolite ”). 
Nearly twenty years later, Leschenault de la Tour was sent by the authorities 
of the Natural-History Museum of Paris on a scientific mission to the Salem district 
in Southern India, and an account of his observations- botanical, zoological, and 
geological—appeared in the official publications of the Museum. j Leschenault’s 
collections are preserved in the Museum d’Histoire Naturelle, and those of the 
Count de Bournon in the College de France, and both these collections have been 
made the object of a series of careful and exact studies by the able mineralogist 
and petrographer M. Alfred Lacroix. § 
Since the time of de Bournon and Leschenault de la Tour, some further 
accounts of the gem-bearing rocks of the Salem district in Madras have been 
published by Newbold,|| J. Campbell A and E. Balfour,** while Dr. King and 
Mr. W. Bruce Foot have described the general geological features of the whole 
district in their memoir “ On the Geological Structure of Portions of the Districts 
of Trichinopoly, Salem, and South Arcot, Madras,”tt and a summary of the results of 
the work of the Geological Survey of India in this district is given in the first 
edition of the * Manual of the Geology of India,’ by Messrs. H. B. Medlicott and 
* “ On the Corundum Stone from Asia,” by the Rt. Hon. Chart,es Greville, ‘ Phil. Trans.,’ 
vol. 88 (1798), PP . 403-448. 
f Ibid., vol. 92 (1802), pp. 233-326. 
X ‘Mem. du Museum d’Hist. Natur. de Paris,’vol. 6 (1820), pp. 329-348; vol. 8 (1822), pp. 245—278. 
§ Bull, de la Soc. Fr. Min.’ (1889), pp. 282-348; see also ‘ Rec. Geol. Surv. of India,’ vol. 24, 
Part III., p. 155. 
|| ‘ Asiat. Soc. Journ.,’ vol. 7 (1843), pp. 150-171 and 203, 204. 
^ ‘Calcutta Journ. Nat. Hist.,’ vol. 2 (1842), p. 281. 
** ‘Select. Rec. Govt. Madras,’ vol. 39 (1857), p. 91. 
+f Memoirs of the Geological Survey of India,’ vol. 4 (1864). 
