By Dave Dyer, Curator Natural History

Nature is full of unusual and fascinating things, but I never thought I would come across a rock that bends! I’m not talking about rocks bending deep underground from the pressure of geological forces, but a rock so flexible that you can bend it with your bare hands. Our natural history collection includes a specimen of Itacolumite, or as I like to call it the “Gumby Stone”.

During our recent move to the new Collections Care Center, we got to handle every specimen while packing. Upon lifting the Itacolumite I was reminded what an odd sensation it is to hold a rock that flexes as you move it. A relatively thin cut section of this sandstone, ours is ¾” thick, will easily bend under its own weight.

Why is it so flexible? Sandstone is made up of irregular interlocking grains of quartz surrounded by small spaces between the grains. This space, which is increased by chemical weathering (i.e. loss of the cementing material), allows for movement of the quartz grains. In a study of Itacolumite from India they found that the pieces of sandstone that had been excavated, and exposed to more chemical dissolution of the quartz, had larger spaces between the quartz grains. This allowed more flexibility compared to stone still deep in the ground.

However, there is no need to go outside and try to bend every rock that you see looking for this particular type of sandstone (and risk getting strange looks from your neighbors!). Itacolumite is found in certain parts of Brazil, India, North Carolina, and Georgia, not in the backyards of Ohio. Our sample was collected in North Carolina and donated to us by Jane D. and Elizabeth U. Sullivant, members of the prominent Sullivant family in central Ohio.

While packing several tons of rocks and minerals in our collection, it was a welcome break to stop and ponder this interesting natural phenomenon that contradicts what we picture when we think of rocks!

Dave Dyer, Natural History Curator