Flexibility is not a characteristic commonly associated with rocks, but there is one remarkable exception: itacolumite, a porous sandstone that turns flexible when sliced into thin strips.
Itacolumite is called after the rock formation where it was discovered, the Pico do Itacolomi in Minas Gerais, Brazil, but it may also be found in Georgia and North Carolina in the United States, and Kaliana village in India. This rock is often used as a construction stone; due to its good partitioning, it can be cut into plates 1 cm thick and up to 20 cm long, which are subsequently utilised mostly as a floor or wall revetment. However, when cut into small strips of only a few centimetres, it demonstrates extraordinary flexibility, which has long captivated geologists.
According to Wikipedia, if a piece of itacolumite 30 to 60 centimetres long is merely supported at its ends, it will bow under its own weight. When turned over, gravity causes it to straighten and bend in the opposite direction. It’s not something you’d expect to see in rocks, but it’s not magic, but science.
For centuries, the flexibility of itacolumite has been the subject of intense discussions among geologists. It was often thought that the presence of tiny scales of mica allowed for some movement between neighbouring grains of quartz, but the flexibility of this interesting rock appears to have a different source.
The porosity of itacolumite appears to allow interstitial mobility, while the hinge-like joints that connect the sand particles keep them together despite displacement.
Those who have held a piece of itacolumite in their hands have described it as a psychedelic sensation, since it has the weight of a rock but flexes easily when pressure is applied to its ends.