Itacolumite

It is also found in Kaliana village (Charkhi Dadri district, Haryana, India),[1] the U.S. state of Georgia, and Stokes and McDowell counties of North Carolina.

[2] On the split faces of the slabs, scales of greenish mica are visible, but in other respects, the rock seems to be a remarkably pure specimen consisting of quartz.

Flakes a millimetre or two thick can be bent between the fingers and are said to give out a creaking sound, but specimens showing this property form only a small part of the whole mass of the rock.

At one time it was ascribed to the presence of thin scales of mica which were believed to permit a certain amount of motion between adjacent grains of quartz.

[2] These features are dependent to some extent on weathering, as the original rock matrix contained constituents which were later removed, leaving open cavities in their place, while at the same time additional silica may have been deposited on the quartz grains, interlocking their irregular surfaces more perfectly together.