168 PHYSIOGRAPHY. 



Diaspore Dioptase. 



Borneo. In Brazil, they occur in the district of Serro do Frio in the ca- 

 pitania of Minas Geraes, and were first discovered in the Riacho Fundo, 

 then in the Rio do Peixe, and also in the Terra de St. Antonio. 



4. Diamond is the most valuable of all the gems. It is employed also 

 in cutting glass, and for engraving, cutting and polishing other hard 

 stones, and the Diamond itself. 



DIASPORE. Tetarto-prismatie Wavelline- 

 Spar? 



Primary form. Doubly oblique prism, according to 

 PHILLIPS. M on T=64 54'. P on T=101 20'. P 

 on M = 108 30'. According to MOHS, it is a rhombic 

 prism of about 130. 



Lustre vitreous and pearly. Color greenish-grey. 



Translucent on the edges. 



Scratches glass. Sp. gr. = 3*4324. 



1. Before the blow-pipe, it decrepitates most violently, and splits into 

 many small scaly particles, possessing a feeble alkaline reaction. 



2. Analysis. 



By VATJQTJELIN. By CHILDREN. 



Alumina - - 80-00 - - 76-06 



Protoxide of iron - - 3 00 7-78 



Water - - 17-30 - - 1470 



BERZELITJS is of opinion that besides these, it also contains some alka- 

 line substance. 



3. Its locality is unknown. 



4. Its reference to the genus Wavelline-Spar is made with hesita- 

 tion, from the limited knowledge possessed of its properties. Unlewi 

 some clue to the discovery of its locality shall ere long be made, it will 

 become doubtful whether it is not an artificial production. 



DICHROITE. (See loliie.) 

 DIOPSIDE. (See Pyroxene.) 



DIOPTASE. Rhombohedral C opper-Bary te. 

 Primary form. Rhomboid. P on P=126 17'. 



