Combination of CDF and D0 results on the mass of the top quark using up $9.7:{rm fb}^{-1}$ at the Tevatron

We summarize the current top quark mass ($m_t$) measurements from the CDF and D0 experiments at Fermilab. We combine published results from Run I (1992--1996) with the most precise published and preliminary Run II (2001--2011) measurements based on $pbar{p}$ data corresponding to up to $9.7:{rm fb}^{-1}$ of $pbar{p}$ collisions. Taking correlations of uncertainties into account, and combining the statistical and systematic contributions in quadrature, the preliminary Tevatron average mass value for the top quark is $m_t = 174.30 pm 0.65:mathrm{GeV}/c^{2}$, corresponding to a relative precision of $0.37%$