Asphaltenes from 136, Canadon Seco (CS), and Hondo (HO) crude oils were separated on a preparatory scale into 20-30 so-called "fine fractions" by sequential precipitation from mixtures of n-heptane and toluene. Chemical analyses were performed to measure the carbon, hydrogen, nitrogen, sulfur, oxygen, and trace metals contents of the fractions. Small-angle neutron scattering (SANS) was performed on fractions dissolved or dispersed in mixtures of toluene-d (or methylnaphthalene-d) and methanol-d to determine the average aggregate size. Statistical analyses were performed to calculate the weighted moments of each elemental parameter assuming that the data were "normally" distributed. High values of the standard deviation and skewness because of the early precipitation of metal oxides and inorganic salts suggested that a Gaussian distribution was inappropriate to describe the behavior of most metals. H/C, N/C, and S/C ratios in B6 and HO asphaltenes appeared to obey a Gaussian distribution, with mean values approximating the average values for the whole asphaltenes. For CS asphaltenes, the initial 10% of precipitated material was generally less aromatic than the remaining fractions. Coefficients of linear correlation were calculated for the chemical composition, solubility, and aggregate size parameters and provided a statistical means of determining the properties of the asphaltene fractions that promoted aggregation and precipitation. Polar and hydrogen-bonding interactions appeared to be more important than dispersion interactions in the precipitation of 136 and HO asphaltenes. In particular, interactions of metalloporphyrins appeared to play a key role in the asphaltene aggregation mechanism. On the other hand, dispersion interactions likely dominated the solubility of CS asphaltenes.