NOTES ON NORWEGIAN MIN RÄLS 1-6. 145 



in twin position according to the common law, twinning-plane : 

 jlOOj. Fig. 8 gives the common type of the twins. One such 

 specimen measures 3 centimeters by 4 along the c-axis and 

 perpendicular to the twinning-plane respectively. 



Univ. Min. Inst. November 1904. 



Explanation of plate V. 



Fig. I. Fergusonite, comb. [231J, [HI], [001]. Högtveit. 



» i'-' n n 5) )) 11 ' [l^lji 11 



„ III. „ with oblique face of [001], „ 



„ IV. „ comb. [230], [HI], [001], [131], 



„ V. Group of pseudomorphs after laumontite. Landsværk. 



„ VI. Monazite, single crystal, comb. [100], [HI]. Søndelev. 

 „ VII. „ twin „ „ 



VIII 



Printed 25 february 1905- 

 Nyt Mag. f. Natiirv. XXXXIII. 11. 10 



