SOME CALCITE CRYSTALS WITH NEW FORMS 



IS 



The negative unit rhombohedron e | 0111 1 , a rare form, is present 

 as three faces, all very small, giving poor reflections. The new form 

 shows only one face, a very narrow one, not striated and giving a 

 fair reflection. It is very close to / { 2134 } with which it occurs. 

 The signal is slightly blurred and measurements of the two sides of 

 the signal gave: 



9& = 17° 25' to 17° 53'; /o = 33° 42' to 33° 44'. 

 calc. = 17° 47'; calc. = 33° 40'. 



While the indices are somewhat complex, if we change them to the 

 orientation given by Goldschmidt {G^ in his Winkeltabellen the 

 indices become { 7297 | and the form fits in well between two known 

 forms. 



6282 (G2) 

 7297 new form. 

 8.2.I0.8 (G,). 



Though occurring but once the form is considered as well estab- 

 lished. The crystal is shown in fig. 8, on which, however, the new 

 form is not drawn, but its position can be easily determined as it lies 

 very close to / { 2134 | . 



SUMMARY 



The new forms for calcite described in this paper are grouped 

 together in the following table, the coordinate angles <j> and p being 

 given for each form. 



Well established new forms 



