Gauge-invariant effective gluon mass from the operator-product expansion

We use the operator-product expansion to find the coefficient of $〈G^2〉$ in Cornwall's minimally gauge-dependent effective gluon propagator to lowest order in ${\alpha }_s$. This contribution to the propagator is explicitly shown to be gauge invariant. The running mass generated by this condensate is obtained to be $m_{\mathrm{gluon}}^2\approx \frac{{\left(640\mathrm{} \mathrm{MeV}\right)}^4}{Q^2}$. Quark condensate effects are insignificant.