353 

 On the Paragenetic Relations of Minerals. 



(Continued from page 152.) 



X. Antimony Formation. — The principal, and, for the 

 most part, sole representative of this formation, is antimonite. 

 With regard to the periods of formation, of which there may 

 be several, it may be regarded as certain that it is more re- 

 cent than the argentiferous and auriferous quartz, and an- 

 terior to the fluo-barytic formations. It is indeed stated to 

 occur likewise in the clinoedritic formation. Its bedding is 

 quartz, rarely ever absent. 



It is a remarkable circumstance that antimonite has al- 

 ways been found to contain at least a trace of gold. In 

 some localities the proportion is sufficiently large for extrac- 

 tion, and even metallic gold is sometimes associated with it. 

 The antimonial minerals by which it is accompanied are 

 kermes, zundererz, berthierite, zinkenite, plagionite, wolfs- 

 bergite, &c. Galena and blende are likewise associated with 

 it sometimes. Barytite occurs frequently implanted. 



The lodes at Wolfsberg (Harz) probably present the great- 

 est variety of constituent minerals, but scarcely anything is 

 known of their order of succession. 



XI. Manganese and Iron Formation. — Hematite, specular 

 iron, and more rarely common brown hematite, are frequently 

 associated with the manganese oxides, especially pyrolusite* 

 which is pseudomorphous, partly after manganite, partly but 

 less frequently after polianite. In some instances the man- 

 ganite and polianite have been found in their normal state. 

 In addition to these occur psilomelan, more rarely braurite 

 and hausmannite. The pseudomorphs after all of these 

 minerals are very numerous. At Laisa (Hesse Darmstadt) 

 there occurs very fine pseudomorphous pyrolusite after man- 

 ganite ; and it would appear that in some instances psilome- 

 lan has been converted into pyrolusite, and that the man- 

 ganese in black, reniform masses, compact and without 

 lustre in the interior, are of this nature. 



In Saxony the association of iron and manganese oxides 

 appears to indicate that the former were first precipitated. 



