\begin{table}%t6
\caption{\label{comp_smithmarconi}Same as Tables~\ref{f_i_cremonese} and~\ref{flusso} but for the mineralogical surface
composition given by \citet{smithmarconi}.}
%\centerline
{\small
\begin{tabular}{cc|cc|cc}
\hline
\hline
 & \multicolumn{1}{c}{Cintala} & \multicolumn{2}{c}{Dermott et~al.}  & \multicolumn{2}{c}{Wiegert et~al.} \\ 
 &   & BM-LB & BM-G
 &  BM-LB & BM-G  \\
 \hline\noalign{\smallskip}
Na & $7.9026\times 10^{4}$ & $3.4231\times 10^{7}$ & $1.9112\times 10^{7}$   & $2.0746\times 10^{6}$ & $1.1583\times 10^{6}$\\
\hline
\end{tabular}}
\tablefoot{$S_{i}$ is given in $N$~cm$^{-2}$~s$^{-1}$.} 
\tablebib{(1) \citet{smithmarconi}.}\vspace{2mm}
\end{table}