Crystal Unit Cell Question

[Uncle Al]

Uncle Al asks a probably silly and very obvious question about some
crystal data...

REFERENCE STRUCTURE = 20626   A,B,C =   5.482   5.482   5.173
   ALPHA,BETA,GAMMA =  90.000  90.000 120.000    SPGR =173 P63     
   3   0 CODEN=   46025 SYMOPS=  389
  40     RFAC= 2.1 ERRFLAG=0 (C-C)ESD=0
   1 Li1    0.00000   0.00000   0.07830
   2 O1     0.24750   0.34220  -0.16200
   3 I1     0.33333   0.66667   0.00000

Lithium iodate, LiIO(3), has two formula units in its unit cell:

2 lithiums
2 iodines
6 oxygens

  ----- Where are the rest of the atoms? -----

 REFERENCE STRUCTURE = 47670   A,B,C =   4.913   4.913   5.405
   ALPHA,BETA,GAMMA =  90.000  90.000 120.000    SPGR =154 P3221   
   2   0 CODEN=   83849 SYMOPS=  398
  40     RFAC= 2.4 ERRFLAG=0 (C-C)ESD=0
   1 Si1     0.46980   0.00000   0.16667
   2 O1      0.41380   0.26510   0.28710

Alpha-quartz, SiO(2), has three formula units in its unit cell,

3 silicons
6 oxygens  

   ----- Where are the rest of the atoms? -----
 
Remember, I am an organic chemist.  We do our best work unclogging
drains and making soybean waste taste like hamburger.  The Devil lies
in the details, so make it simple for a simple person.  Post 'em if
you've got 'em!

Thank you.

-- 
Uncle Al
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