A phosphate ore from the Drymona-Epirus area (northwest Greece) was ground and sieved ( (<40,40-63,63-125,125-250), (250-500), and (500-1000 \mu \mathrm{m}) ). The particle fractions obtained were examined for their structure by XRD and for their specific surface area by (\mathrm{N}{2}) adsorption (BET). Chemical analysis and SEM photography were also performed. Crystallographically, the sieved particles consist mainly of apatite and quartz. The size of the crystallites of those two components, as determined via the Sherrer relationship, increases as the size of the particles decreases, from 72 and (66 \mathrm{~nm}), respectively ( (500-) to (1000-\mu \mathrm{m}) fraction), to 99 and (80 \mathrm{~nm}) (125- to (250-\mu \mathrm{m}) fraction). Then between this and the next fraction ((63-125 \mu \mathrm{m})), the sizes of the crystallites drop almost to the original values and thereafter increase again to 82 and (79 \mathrm{~nm}), respectively, in the last fraction ((<40 \mu \mathrm{m})). The surface fractal dimension (D) of the particles as determined from surface area measurements via (\mathrm{N}{2}) adsorption (BET) is (D=2.00 \pm 0.01) for particles with diameter (d \geqslant 200) (\mu \mathrm{m}) and changes to (D=3.00 \pm 0.01) for particles with (d \leqslant 200) (\mu \mathrm{m}). This surface dimensionality remains unaltered when the samples are heated to (400^{\circ} \mathrm{C}). The alteration of surface dimensionality and the abrupt drop in the crystallite size at (d \approx 200) (\mu \mathrm{m}) are accompanied by some profound changes in the chemical composition of the particles. Thus larger particles appear rich in (\mathrm{P}{2} \mathrm{O}{5}) and poor in (M_{2} \mathrm{O}_{3}(M=\mathrm{Al}, \mathrm{Fe})) and vice versa. SEM photography indicates a flake-like structure for larger particles while the smaller ones appear more robust. These results agree with the assumption that the larger phosphate ore particles possess a layered-type structure down almost to (200 \mu \mathrm{m}), while smaller particles appear invariant in three dimensions. (2) 1995 Academic Press, Inc.
Key Words: phosphate ore; fractal dimensioning.