  The electrical, in-plane resistance as a function of temperature $R(T)$ of
bulk and mesoscopic thin graphite flakes obtained from the same batch was
investigated. Samples thicker than $\sim 30$ nm show metalliclike contribution
in a temperature range that increases with the sample thickness, whereas a
semiconductinglike behavior was observed for thinner samples. The temperature
dependence of the in-plane resistance of all measured samples and several
others from literature can be very well explained between 2 K and 1100 K
assuming three contributions in parallel: a metalliclike conducting path at the
interfaces between crystalline regions, composed of two semiconducting phases,
i.e. Bernal and rhombohedral stacking. From the fits of $R(T)$ we obtain a
semiconducting energy gap of $110 \pm 20$meV for the rhombohedral and $38\pm 8
$meV for the Bernal phase. The presence of these crystalline phases was
confirmed by x-ray diffraction measurements. We review similar experimental
data from literature of the last 33 years and two more theoretical models used
to fit $R(T)$.
