On Rhodizite, a New Mineral Species from Russia. 33 



veral separate crystals, which together weighed 0.386 grains, 

 was found to be 3.415. By an alteration of temperature, the 

 crystals exhibit strong polar electricity. The electrical axes, as 

 in the boracite, unite the two opposite three-sided solid angles 

 of the dodecahedron, and are therefore four in number ; those 

 angles on which there are tetrahedral faces exhibit positive 

 electricity, and the others negative, during a diminution of tem- 

 perature ; but during an increase of temperature the case is re- 

 versed, for the first exhibit negative, and the last positive elec- 

 tricity. When exposed to the blowpipe, the rhodizite displays 

 a bright green flame ; but there is also a tinge of red. Profes- 

 sor Rose has not analysed the substance, as he expects to receive 

 larger specimens ; but a qualitative examination afforded no trace 

 of hthion ; and it is therefore to be supposed, either that the 

 quantity in the very small portion examined was too minute for 

 detection, or that, as is sometimes the case, the red tinge of the 

 flame was derived from the lime. 



The electrical phenomena of the rhodizite give additional pro- 

 bability to the opinion, that not only in its crystalline form, but 

 also in its atomic constitution, this mineral is identical witli bo- 

 racite, and hence that it is isomorphous with it. It is possible 

 that the rhodizite is nothing else than a lime-boracite, just as 

 the common boracite is a magnesia-boracite. It has hitherto been 

 found in two localities, viz. at Sarapulsk, a village which, 

 according to Georgi [Physko-geographical and NaturaUiisto- 

 r'ical Description of the Russian Empire, vol. iii. p, 189) is 

 about 12 wersts from Mursinsk, a town about 100 wersts north 

 from Catharinenburg ; and at Schaitansk, situated about 72 

 wersts north from Catharinenburg. At the latter locality the 

 crystals are larger, some having been found about two lines in 

 diameter ; at Berlin there is a specimen of the granite of this lo- 

 cality, on which the crystals of Rhodizite are partly superim- 

 posed on cry.stallized quartz, partly imbedded in red tourm^- 

 hne, and partly contained in a clay occurring in the small cavities 

 between the constituent parts of the matrix. 



Vol. XXIII. NO. XLv.— JULY 1837. ,, 



