La3Ga5.5Ta0.5O14 shows promise for high temperature, high frequency crystal resonator applications. We report on two methods for thinning wafers of this material. Using wet chemical etching, we found that HCl-or HF-based solutions produced etching at room temperature, while HNO3 and H3PO4 produced practical rates at greater than or equal to 70 degrees C. In all of these solutions, the etching was reaction-limited with activation energies > 14 kcal . mol(-1). Some degree of surface smoothing was achieved with HCl etching at elevated temperatures. The near-surface stoichiometry was unaffected by the wet etch treatments. Using dry etching, we found that Cl-2-based discharges produced rates < 950 Angstrom . min(-1) under all conditions, with Cl-2/Ar maintaining the best surface morphology.