What is the primary characteristic of the 'moon rock' that Dr. Throckmartin and Stanton discovered in Nan-Tauach?

The primary characteristic of the 'moon rock' discovered by Dr. Throckmartin and Stanton in Nan-Tauach is its subtly different color, tinged with grey and possessing a peculiar 'deadness'^[1]. Upon touching it, a shock of 'frozen electricity' tingled through the nerves, indicating it was a chill force rather than ordinary cold^[1].

This slab of stone, about fifteen feet high and ten wide, was also identified as a door due to a smooth, semicircular depression at its base and seven small circular indentations on convexities above its lintel, which Stanton believed were what opened it^[1][1].