MINERALOGY, 305 



4. Magnesia. This earth is light, tasteless, of a perfectly 



white colour, and like the preceding, is infusible except 

 by Voltaic electricity. 



T-iis is not so abundant as the preceding earths, but is 

 found in the composition of several earthy, as well as metal- 

 liferous substances. Native Magnesia which produces this 

 mineral in its purest state, is a substance of rare occur- 

 ence, and has only been met with in New Jersey. 



5. Zircon. Is white, tasfeless, rough to the touch, insolu- 



ble in v/ater, and infusible except as the preceding. 



This earth is but sparingly four.d ; and is at present only 

 knort-n to enter into the composition of three substances, the 

 Hyacinth, the Jargoon, and the Zirconite ; all of which are 

 occasionally used by Jewellers. 



r>. Glucive. When purs this is white, sof"", unctuous to the 

 touch, and of a sweet taste, from which circumstance it 

 derives its name. 



Glucine has only been defected in combination with other 

 substances. 'I'he Eacla^e, Aquamarine, Emerald, and Ga- 

 dolinite; these Minerals though not abundant, are occasi- 

 onally found in mountainous countries. 



7. Yttria. This earth possesses several properties in com- 

 mon with the last, like which it has a sweetish taste ; 

 but it is five times, whilst Glucine is only three times 

 heavier than water. 



y 



