We demonstrate that pion and (anti)proton transverse mass spectra
at central rapidity in RHIC Au+Au collisions can be obtained by
coalescence of thermal, distributed-mass partons. The energy
distribution in the thermal bath reference frame is taken to be
a cut power-law distribution, incorporating this way also moderately hardpartons in the equilibrium statistical model. We study the thermodynamical properties (equation of state, sound propagation) of such a quark matter in a consistent quasi-particle framework.