56 A. F. Rogers — Baddeleyite from Montana. 



test is proof that zirconium is present. The acid solution of 

 the soda fusion with ammonium hydroxide gave a white floc- 

 culent precipitate which is insoluble in KOH, but soluble in 

 oxalic acid. The sulphuric acid solution with ammonium 

 hydroxide gave a precipitate which glows when heated in 

 platinum forceps before the blowpipe. 



Baddeleyite as a Hock-forming Mineral. — Baddeleyite is 

 one of the rare accessory minerals of igneous rocks. As -far as 

 known, it is confined to rocks low in silica, the jacupirangite of 

 Brazil having only 38 per cent Si0 2 , and the present corundum- 

 syenite about 44 per cent. The deficiency in silica is proba- 

 bly the reason baddeleyite forms rather than zircon. 



Identity with Baddeleyite. — From the presence of zirconium 

 and the crystal habit one might call the mineral zircon, badde- 

 leyite, or one of the zirconium-pyroxenes, lavenite, wohlerite, 

 or hiortdahlite. It is distinguished from zircon by luster, hard- 

 ness, and cleavage ; from altered zircon by the absence of water, 

 and from the three zirconium pyroxenes mentioned by the 

 solubility and fusibility. The angles in the prism zone 

 [100 : 110 : 010] agree better with the baddeleyite angles than 

 with the angles of the other minerals. The sum total of the 

 characters undoubtedly identifies the mineral as baddeleyite. 



Stanford University, California, September, 1911. 



