The crystal structure of pargasite from a cut gem from Myanmar, (K0.094Na0.93)(Na0.15Ca1.78)(Mg4.51Fe2+0.02Al0.53Ti0.10)(Si6.56Al1.44)O22(OH1.32F0.68), a 9.882(6), b 17.973(11), c 5.282(3) Å, β 105.20(1)°, V 905.33(17) Å3, space group C2/m, Z = 2, has been refined to an R1 index of 1.9% using MoKα single-crystal X-ray diffraction. The unit formula (calculated from the results of electron-microprobe analysis), the refined site-scattering values, and the observed mean bond-lengths, were used to assign site populations. Al occurs at both the T(1) and T(2) sites, but is strongly ordered at T(1). Al is disordered over the M(2) and M(3) sites, but is excluded from the M(1) site. ANa is split between the A(2) and A(m) sites with minor K assigned to the A(m) site. The frequencies of short-range ion arrangements over the configuration symbol M(1)M(1)M(3)–O(3)–A:T(1)T(1) were calculated from the refined site-populations and are in reasonable accord with the fitted infrared spectrum of this amphibole in the principal OH-stretching region.