177 



the faces of which seem to be perfectly simple. The planes of 

 the pyramidal forms are all smooth and very brilliant. Those 

 of the form x considerably exceed in size those of the form .s. 

 The determination of the different forms is founded on the 

 following angular values. 



Measured Calculated 

 m:c = (lOTo) : (OOOl) = 90° 9' 90° 

 a:c = (1120) : (0001) = 89° 57' 90° 

 m : m = (lOTo) : (OlTo) = 59° 58' 60° 

 a : Ш = (1 120) : (l0T"0) = 29° 24' 30° 

 s:c = (1121) : (OOOl) = 55° 39' 55° 45V2' 

 x:c -^ (ion) : (OOOl) = 40° 13' 40° I8V2' 



The apatite crystals belonging to this type are nearly colour- 

 less, only showing a faint tinge of wine-yellow. They are almost 

 perfectly translucent, apart from the fact that they are traversed 

 by numerous cracks mostly running parallel to the faces of the 

 fundamental prism. 



The same detached crystal on which the angular measure- 

 ments were made , was also used for the determination of the 

 specific gravity of the mineral. By weighing in benzole this 

 was found to be 3,175. 



The scanty supply of material did not allow of a chemical 

 investigation of the mineral. 



The specimen on which the apatite crystals now described 

 occurred was found lying loose at the locality No. 12. Besides 

 the apatite the specimen consists chiefly of elpidite. This 

 mineral never intrudes into the apatite crystals; and when such 

 a crystal has been detached, the elpidite presents brilliant 

 contact surfaces. Consequently the elpidite is here a younger 

 formation than the apatite. Other minerals occurring on the 

 specimen are feldspar, aegirine and parisite , the last mineral 

 being younger than the elpidite. 



12 



