93 



CERIUM GROUP. 



There li-as, of recent years, been some demand for minerals Case 73. 

 containing certain rare elements, more especially thorium, which 

 is used in the manufacture of mantles for incandescent lamps. 



-A resinous, brownish mineral ; can be easily scratched with a Monazite. 

 knife. 



2641, Vegetable Creek : coarse sand. 



6725, The Gulf, New England : in parent rock. 



6974, Tooloom River : zircon sand containing some monazite. 



2115, Tumbarumba : zircon sand containing some monazite. 



2639, probably from New South Wales : a large piece. 



9276, Dingo Creek, Torrington : in quartz. 



9705, Warialda District; associated with carbonate of bismuth. 



BOGHEAD MINERAL. 



Boghead Mineral, or Kerosene Shale as it is popularly called, CaSG 72, 

 occurs in seams and irregular layers in the coal measures. Jt 

 contains a much higher percentage of volatile hydrocarbons than 

 true coal. A good shale would yield 150 gallons of crude oil per 

 ton, or 18,003 cubic feet of gas. It is very advantageously mixed 

 with ordinary coal in the manufacture of gas. The principal 

 deposits are those of Joadja, Hartley, and Capertee Yalley, but 

 it has been found at many other places. JMear the entrance 

 will be found block specimens showing the thickness and general 

 character of the seams at these places. Specimens are exhibited 

 from many localities, but at the time of writing (December, 1901) 

 the collection is in course of arrangement. 



Good shale breaks with a characteristic conchoidal fracture. 

 For a good specimen from Hartley, showing this fracture and 

 concentric markings, see case 138. 



