PHYSIOGRAPHY. 165 



Rhomb Spar Rionite. 



1. Before the blow-pipe, and also from long exposure to the weather, 

 it turns brownish-black. 



2. Analysis. 

 By BROOKE. 



Carbonate of iron and carbonate of magnesia, in the ratio of 1-315 of 

 the former to 8-685 of the latter. 



3. The varieties of the present species have often been found accom- 

 panying those of Dolomite ; it also occurs in chloritic steatite. 



4. It occurs at various places in Salzburg, Tyrol and Switzerland, 

 also in Unst, one of the Shetland Isles. In the U. S. at Marlborough, 

 (Vt.) in steatite ; at Middlefield, (Mass.) and generally, in most of the 

 soapstone quarries of New England. 



APPENDIX TO RHOMB SPAR. 

 i. Hystatic Carbon- Spar. BREITHAUPT. 

 P on P =107 28' 20". 



Cleavage, very perfect parallel with the primary form. 

 Hardness =5-5 . . . 5-75 (scale of BREITHAUPT.) Sp. gr. = 

 3-040 . . . 3-089. 



It is not believed to be a very rare species. Localities quoted, are 

 the Hartz, Erbendorf in the Fichtelgebirge. 



RIONITE. Selenious Malacon e-Blen de. 



Primary form. Unknown. Massive : composition gran- 

 ular. 



Color cochineal-red, to lead-grey. Streak of the lead- 

 grey variety, blackish. 



Sp. gr. =5'5 . . . 5-6. 



1. Under the blow-pipe, it burns with a beautiful, violet-colored 

 flame, attended by much smoke, and the peculiar odor of selenium. 

 2. Analysis. 

 By DEL Rio. 

 The grey colored variety. 

 Selenium 49-00 



Zinc 24-00 



Mercury 19-00 



Sulphur 1-50 



which, with the addition of 6 p. c. of lime mechanically intermingled, 



