The atomic structure of tubular subcrystals of beta-iron(III) oxide hydroxide.

The presence of pores in beta-FeOOH (mineral name akaganéite) has been confirmed by pore volume distribution measurements. The mean pore diameter has been found (28.4 A) and the number distribution calculated. With the available evidence from electron microscopy, gas adsorption and X-ray diffraction a unique superstructure for the porous subcrystals is deduced which, because of their unusually small dimensions, can only be formulated in atomic terms.