BRIEF DESCRIPTION: The cap of A. grauiana is 60 - 90 (-200) mm wide, semi-globose, later planar with depressed disc, with a short striate margin extending slightly beyond the end of the gills. The margin is not truly appendiculate but sometimes bears parts of the ring and volva. The cap is approximately gray-brown. The flesh is white and thins evenly to the margin. The volva is present in large plaques which are thickest over the disc and cinnamon to sordid brownish ochre in color.

The gills are free, white to pale leather colored, with edges at first concolorous with gill face, later grayish red-brown.

The stem is 75 - 135 (-235) × 18 - 24 (-28) mm, bearing mixed colors tinted with lilac, later lilac-red-brown, and linearly striate near apex. The bulb is only slightly broader than the stem at maturity, and the ring is present in young material but may disappear in older material. The flesh is white and solid,  rarely hollow. The volva is present as scattered warts near the stem base, poorly developed, as warts or a brief weak limb.

The spores measure (9.0-) 10.8 - 16.5 (-17.0) × (7.9-) 8.0 - 10.3 (-14.0) µm and are ellipsoid, occasionally broadly ellipsoid, occasionally elongate and inamyloid. Clamps are present at the bases of basidia.

The following are all reportedly absent from A. grauiana: amanitins, phalloidin, muscimol, and muscarin.

Amanita grauiana is solitary and mycorrhizal in forests with Nothofagus glauca or N. obliqua mixed with Chusquea.

The present species seems so close to the following that the names may be taxonomic synonyms: Amanita ushuaiensis (Raithelh.) Raithelh. and Amanita merxmuelleri Bresinsky & Garrido.