Dr Petzholdt 07i the Formation of the Diamond 321 



crystalline structure of diamonds does not militate against this 

 conclusion ; for honeystone is regularly crystallized, although 

 it is undoubtedly of vegetable derivation, as is proved not only 

 by its chemical composition, but also by its mode of occur- 

 rence. 



Lastly, we now arrive at our own view of the formation of 

 the diamond, and it coincides completely with that of New- 

 ton, Jameson, and Brewster ; but we base it neither on its 

 strong refractive power, nor on the great hardness which the 

 carbon has acquired in the diamond, nor on its polarising pro- 

 perties, for we are supported by entirely different considera- 

 tions. We believe that, according to the present state of our 

 knowledge, the diamond is a product of the newest geological 

 period, resulting from the slow decomposition of a vegetable 

 substance. Let us now shortly adduce the proofs of this 

 opinion. 



That the diamond must be a product of the youngest geolo- 

 gical epoch, of the so-called historical epoch* in a geological 

 sense, appears from the fact, that hitherto it has only been 

 met with in stony deposits, which decidedly belong to the 

 youngest formations, as I have more fully stated in another 

 place. Its primary repositories, that is to say the places where 

 it was formed, cannot be very different nor very remote from 

 its secondary repositories, that is, from those places where we 

 now meet with it ; and all the mineral bodies which we are 

 in the habit of regarding as the more or less constant asso- 

 ciates of the diamond in diamond sands, are merely accidental, 

 if I may so express myself. There is not the slightest reason 

 for assuming that the formation of the gold or platina, &c., 

 stands in any nearer connection with the diamond, for platina 

 and gold are found in many localities without diamonds. These 

 bodies were eitheratthe locality when the diamond was formed, 

 or tlicy were transported along with that substance by water. 

 And although it cannot be denied in regard to some of the 

 other ingredients of the diamond-sand, such as some of the 

 minerals belonging to the quartz genus, viz., quartz, calcedony, 

 and hornstone, and also brown ironstone, that they were formed 



* Petzholdt'8 Erdkundc {Geologk), p. 87. 



