AMBER AND IRON PYRITES, 



193 



Carbon crystallises in yet another and totally different 

 form, namely, in black, opaque, six-sided plates, when it is 

 called graphite, plumbago, or "black-lead." This may very 

 well be derived from the decay of vegetable matter ; and jet 

 is considered to be a highly bituminised wood, which, from 



/- 



Fig. 38. ANIMAL REMAINS IN AMBKK. 



the fact that it is often found surrounding fossils, &c., seems 

 to have hardened from a plastic if not liquid condition. The 

 rocks in which it is found are often strongly impregnated 

 with petroleum. 



Amber is the resin (Fig. 38) of some extinct speciesof pine, 

 and is often found with coal or fossil wood. Many pines and 

 firs at the present day have resin between their annual rings ; 

 and large masses of gum are found at the roots of the New 

 Zealand Kauri pine, and exported to the amount of several 

 thousand tons every year for the manufacture of varnish. 



