101 



of the common, lengthened form in closely crowded masses; 

 sometimes transitions between both forms are found; of accom- 

 panying minerals are only found quite small brown tables of 

 a mica-like mineral. 



Cordylite. 



Of this mineral a few crystals have been found differing 

 from those previously known ^), both in form and especially by 

 being completely fresh, so that, with regard to physical pro- 

 perties, they almost appear as a quite new mineral. 



The crystals are of a size of up to 1 mm in diameter, and 

 of the form shown in fig. 3; they are bounded by c{000l}, 

 ш{10Г0}, q{\On}, r{2023}, and the 

 new form s (4043}. Contrary to the 

 previously known crystals the form 

 j?{4.0. 4. lo), which in these is very pre- 

 dominant, is wanting, and tn is here 

 quite slightly developed, so that the 

 crystals become far shorter than those 

 known before. All the faces are very 

 bright; the basis and the faces of q are also generally quite 

 plane, while the other surfaces are highly striated horizontally, 

 and so the measurements are not so exact, as might otherwise 

 have been expected. The new form s (4043} has been deter- 

 mined by the following measurements: 



^ — ' ^ 





(Sk 



^1 .J' 



-^l^r^^rr^ 



Л. — s : 



4 nv 



^ :— " 



a- r: 



- . . . ^_^,_;^— - 





^ ^ 





^\" ' / — i-^ 



Fig. 3. Cordylite; 

 Narsarsuk. 



Number 



of mea- Variations, 

 surements. 



^:c = (4043):(000l) = 79°14' 7 78°31'-80° 1 1' 79° 8|' 



Average 

 value. 



Calculated 

 value'-). 



As will be seen, this form, as all the pyramids of this 

 mineral previously known, has an index for the c-axis which 

 is divisible by 3, and therefore it must, strictly speaking, be 



'^) Described by Flink in: Medd. om Grønl. 24, 1901, p. 42. 

 -) After the axial ratio с = 3.3865 given bv Fltnk. 



