PRO dustem_write_mix,dir,st

IF ptr_valid(st[0]) THEN BEGIN
  comments=(*st[0]).comments
  Ncomments=n_elements(comments)
ENDIF ELSE BEGIN
  Ncomments=0L
ENDELSE

Nst=n_elements(st)

frmts=[ $
         '(A)', $
         '(A)', $
         '(A)', $
         '(A)', $
         '(A)']

;Start loop over type of grain

FOR i=0L,Nst-1 DO BEGIN
  ;Test if the pointer is pointing to something
  IF ptr_valid(st(i)) THEN BEGIN
        ;Get filename

        ffile=(*st(i)).file
        fv=str_sep(ffile,'/')
        file=dir+fv(n_elements(fv)-1)

        ;Open file
        message,'Will write MIX file '+file,/continue

        openw,unit,file,/get_lun

        ;Print comments
        IF Ncomments NE 0 THEN BEGIN
          FOR ii=0,Ncomments-1 DO BEGIN
             printf,unit,comments[ii]
          ENDFOR
        ENDIF
        ;Print FMIX

        FOR k=0L,n_elements((*st(i)).fmix)-1 DO BEGIN

            printf,unit,((*st(i)).fmix)(k),format=frmts[k]

        ENDFOR
        close,unit
        free_lun,unit

   ENDIF ELSE BEGIN
      ;left blank intentionally
   ENDELSE
ENDFOR

END