Type II donor‐acceptor pair spectra involving the shallow group IIA acceptor Mg and the group VI donors S and Te have been observed from GaP crystals grown from Ga solution in an open‐tube furnace system. Magnesium can be an optically active inadvertent contaminant in high‐purity GaP. Crystals containing ∼1017cm−3of these desired impurities, added intentionally, exhibited sharp structure due to electron‐hole recombinations at discrete donor‐acceptor pairs, with negligible contamination from unwanted spectra. The transition energies in these spectra can be closely fitted for shell numbersm≳20(pair separation≳17 Å) by an expression which includes only the coulomb monopole term for the final state interaction and a van der Waals term for the initial state interaction, using low‐temperature static dielectric constant. This analysis yields the activation energy of the Mg acceptor in GaP, (EA)Mg=53.5±1 meV, substantially different from previous estimates derived from electrical transport and impurity Raman scattering measurements. Trends in the activation energies of the three Ga‐site acceptors and three P‐site acceptors known in GaP are discussed qualitatively.