o24 The Paragenetic Relation*, of Minerals. 



directed his attention to these points, and has arrived at 

 a number of very interesting results. Of these, and the infer- 

 ences he draws from them, his general views, and the argu- 

 ments by which he supports them, it is the purpose of the 

 following pages to give some account. By the paragenesis 

 of minerals he understands the more or less definite mode 

 of association, by means of which he endeavours to deter- 

 mine their relative age; and he has conducted his observa- 

 tions from the point of view expressed in a remark of 

 Dolomieus, that every stone must have some connection 

 with the general history of our globe, and although individu- 

 ally it may possess but little interest, still in its relations to 

 others it may lead to important discoveries ; further, that it 

 is the study of the most common and most universal mine- 

 rals, and from which valuable results may chiefly be an- 

 ticipated. He in the first place brings forward some facts 

 which are sufficient to shew that the paragenetic relations 

 of minerals are deserving of being studied not only by the 

 mineralogist but perhaps still more so by the geologist and 

 the chemist. 



In some instances the existence of a mineral species 

 appears to depend upon the co or pre-existence of another 

 mineral. Thus among epidotes, which are tolerably abundant, 

 manganesian epidote occurs only in association with heter- 

 ocline, consisting chiefly of oxide of manganese ; and among 

 the titanites, which are still more frequent, greenovite 

 occurs at St Marcel in Piedmont, only together with the 

 above two minerals. Basaltine is the only amphibole, seme- 

 line the only titanite, melanite the only garnet, and hyacinth 

 the only zircon which occur in trachytic basalt or phonolite. 

 Rhodizite has hitherto only been met with upon turmalin. 

 There are again other minerals, whose existence may safely 

 be said to depend upon the pre-existence of copper pyrites ; 

 thus bismuthine, linneite and cobalt glance. Magnetic 

 pyrites very generally accompanies copper pyrites, which is 

 in this instance the most recent. It is perhaps still more 

 remarkable, that all larger masses of variegated copper 

 pyrites are accompanied by the more recently-formed cop- 

 per pyrites, and the larger masses of copper pyrites by 



