The powder pattern of calcium gaiactarate tetrahydrate (CaC 6 H 8 O 8 -4H 2 O) is presented. The compound was found in white wine stored for 4 years. A Rietveld refinement using the atomic coordinates from a single crystal study as starting values was refined with 55 parameters and without preferred orientation to R B = 5.97%, R F = 4A4%, R p = 10.39%, and R wp = 13.43% for 84 reflections. Crystal data: M r =320.14, orthorhombic, Pcan, a = l.3359(1) A, b= 11.6296(3) A, c = 15.0978(6) A, V= 1288.05(6) A 3 , Z=4, D x = 1.651 g/cm 3 , \(CuATa 1 )= 1.54060 A, jx, = 46.76 cm '. © 2000 International Centre for Diffraction Data. [S0885-7156(99)