t 



Biographical Memoir of M. Hauy. 217 



the alleged blue schorl of Dauphii))' has u right prism as a nu- 

 cleus. He therefore separated both from the schorl genus *. 



At a later period, he distinguished the electric schorl or tour- 

 maliite^ from the black schorl of the primitive mountains. The 

 nucleus of the former is a regular hexahedral prism, while that 

 of the latter is only tetrahedral f. 



He continued his researches. Each of these alleged schorls 

 he found to jx)ssess determinate characters, to grqup itself with 

 the varieties which really belong to it, and to be isolated from 

 those which had been improperly associated with it. Similar, 

 operations disclosed the differences between the minerals that • 

 had been confounded together under the name of zeolites j, and 

 in all cases chemistry and physics, excited to action by these 

 results of crystallography, discovered in their turn characters or 

 elements in these minerals, which they had previously failed to 

 bring to light. 



From this moment M. Haiiy was no longer a mere experi- 

 menter in physics : he was preparing himself to become the le- 

 gislator of mineralogy ; and, in fact, it may be said that the 

 new era of that science dates from his researches into the struc- 

 ture of the schorls, and that since this period the study of the 

 crystalhne structure of minerals has each year produced some 

 unexpected discovery. 



Among the schorls, M. Haiiy at length came to distinguish 

 fourteen species. He discovered six among the zeolites, four 

 among the garnets, and five among the hyacinths. In this way, 

 he not only announced to chemists, that, by recommencing their 

 analyses, they would find in these minerals differences of com- 

 position which they had misinterpreted, but he also very fre- 

 quently predicted that the differences, which they imagined they 

 saw, could not exist. And, in this manner, from the indications 

 furnished by crystallography, M. Vauquelin succeeded in find- 



• Notice respecting the Structures of the Crystals of Schorl, read to the 

 Academy on the 30th March 1787, printed in the Journal de Physique of 

 1787, p. 322. 



f Journal d'Histoire Naturelle, torn. ii. p. C7, printed in 1792. After- 

 wards M. Haiiy preferred the rhomboid for tourmaline ; but these two forms 

 are not incompatible. 



X Journal des Mines, No. xiv. p. 80. 



