This rock is a form of silica that contains micro-crystalline quartz.

It is composed of flysch containing quartz, limestone, marl, and other conglomerates.

The clay body can contain black iron ore, mica, and quartz, all in a matrix of sediment.

Biotite is a common mineral in these rocks, which often contain also much quartz and alkali felspar.

One explanation involves intense electric fields created piezoelectrically by tectonic movements of rocks containing quartz.

However, the Australian version contains kaolin and quartz instead of silica for abrasives.

Mohawkite, particularly when it contains quartz, is often used in jewelry because of its appearance.

The soil of the national park contains quartz and marble.

In addition they also contain quartz and kaolin, plus small amounts of other clay minerals and organic matter.