( 29<2 ) 

 On Miargyrite and Jamesonite. 



I. MIARGYRITE. 



This mineral, formerly confounded with tlie Red Silver-ore, 

 was first separated from it by Mobs, under the name Hemi- 

 prismatic Ruby Blende. H. Rose of Berlin adopts the view of 

 Mobs, but gives to the substance the name of Myargyr'ite, from 

 cieyvpo^, silver, and fiinnv, less, because it contains less silver than 

 red silver-ore. It is found at Braunsdorf in Saxony. On ana- 

 lysis, it afforded 



Sulphur, 21.95 



Antimony, 39.11 



Silver, ...... 36.40 



Copper, 1.06 



Iron, 0.62 



99.17 



As 36.40 of silver take up 5.4-1 of sulphur, in order to form 

 sulphuret of silver, and 39.14 of antimony and 14.65 sulphur, 

 the quantity of sulphur in sulphuret of antimony is to that in 

 sulphuret of silver as 3 to 1. This mineral contains, besides, 

 small quantities of sulphuret of silver, sulphuret of copper, and 

 sulphuret of iron. 1.06 parts of copper take up 0.54 of sul- 

 phur, in order to form the highest sulphur state ; and 0.62 parts 

 iron require 0.74 parts sulphur and 0.62 parts iron, to form 

 sulphuret of iron. The composition of this mineral, which is 

 analogous to that of the zinkenite, is expressed by the follow- 

 ing formula, 



Sb + Ag. 

 It results from this composition, that this mineral has the 

 same constituent parts as dark red silver-ore, but in very diffe- 

 rent relations, so that it cannot be viewed as a mere variety of 

 red silver-ore, but as a distinct species. 



II. JAMESONITE. 



This mineral occurs in Cornwall and in Hungary ; but in 

 neither is it abundant. 



It was first described by Mohs, under the name Axotomous 



