Shintouite is a stone found in and around Kasumor.
It hardens when more pressure is applied to it, provided the stone is strong enough to withstand the initial impact. The stone starts out soft, with a similar consistency to chalk, but by slowly increasing the pressure exposure, it can become almost infinitely hard and durable. This also means that how older a structure is, the more solid it becomes and as such also more resistant to wear and tear, including winds and water damage. Most Kasumor “ruins” are still in pristine condition, since they are made of Shintouite. The mountains themselves are weathered at the top, but still very steep and high when compared to mountain ranges of the same age, due to the strengthening effect.
Shintouite has become a popular building material across Telluris, especially for fortifications. It is never, under any circumstances whatsoever, to be used to build sewers in the Hurosha Empire. Really.