Itacolumite, flexible sandstone and flexible quartzite – a review

Flexible quartzitic rocks are found in various locations around the world and have been identified as both sandstones and quartzites. The term itacolumite was first used for a Brazilian quartzite thought to be a new type of rock in 1822. As analytical methods have improved flexibility has been shown to be due to irregular interlocking quartz grains surrounded by regular intergranular spaces. Platy minerals such as muscovite are sometimes present and probably add support to the structure, but are not necessary for flexibility. The underlying cause of the texture appears to be chemical dissolution of quartz at the grain boundary.