Asuka 881394 is a unique magnesian eucrite with pyroxenes that are Mg-rich like those of cumulate eucrites, but with a granulitic texture unlike the textures of cumulate eucrites. Plagioclase compositions are ~An 9 8 , and are even more calcic than those in cumulate eucrites. Pyroxene does not show pigeonite-to-orthopyroxene inversion textures, suggesting different crystallization conditions than those of cumulate eucrites. Mn-Cr isotopic analyses determined initial 5 3 Mn/ 5 5 Mn=(4.6+/-1.7)x10 - 6 and initial ε( 5 3 Cr) I =0.25+/-0.17 in A881394. This initial 5 3 Mn abundance corresponds to a formation interval Δt L E W =-6+/-2 Ma relative to the LEW86010 angrite, implying an 'absolute' age of 4564+/-2 Ma. Both the initial 5 3 Mn abundance and the initial ε( 5 3 Cr) I value for A881394 are identical to those previously determined for the HED parent body at the time of its differentiation. Al-Mg isotopic analyses determined initial 2 6 Al/ 2 7 Al=(1.18+/-0.14)x10 - 6 , from which a formation interval Δt C A I =3.95+/-0.13 Ma is calculated relative to the canonical value 2 6 Al/ 2 7 Al=5x10 - 5 for CAI. Combining this formation interval with a recently reported Pb-Pb age of 4567.2+/-0.6 Ma for CAI gives 4563.2+/-0.6 Ma as the age of A881394, in excellent agreement with the age based on the Mn-Cr formation interval. Alternatively, the 5 3 Mn and 2 6 Al formation intervals of A881394 allow the Mn-Cr and Al-Mg timescales to be intercalibrated, suggesting that an 'absolute' CAI age of 4568 Ma is most consistent with the 4558 Ma Pb-Pb age of LEW86010. The initial 2 6 Al abundance existing in A881394 would have been insufficient to cause global melting in the HED parent body (probably asteroid 4 Vesta). Nevertheless, it could have been derived by radioactive decay over only ~2 Ma from an abundance that would have been sufficient to cause global melting. The higher value of molar Mg/(Mg+Fe)=0.57 for A881394 than those of the ordinary (basaltic) eucrites (Mg/(Mg+Fe)=0.30-0.42) suggests additional factors may have been important for magma genesis on the parent body. If 2 6 Al were the only heat source, partial melting would have been the major process in the interior of the parent body, and Mg/(Mg+Fe) would be lower in the melts than in the primordial source material. Late-stage accretion could have supplied relatively magnesian primordial material to the surface of the parent body, thereby increasing Mg/(Mg+Fe) in a shallow magma ocean from which A881394 crystallized, and also may have augmented 2 6 Al heating. The granulitic texture of A881394 may have been produced during residence in the thin, earliest, crust, kept hot by the magma beneath it. If 2 6 Al was, nevertheless, the major heat source for asteroidal melting, it may account for declining post-accretion heating of main belt asteroids with increasing heliocentric distance.