semiflint

Example:The tool makers prefer to use flint due to its hardness and ability to produce sharp edges.

Definition:A hard, homogeneous form of sedimentary rock, composed of quartz, typically found in layers.

Example:The white cliffs of Dover are primarily composed of chalk, which is highly resistant to erosion.

Definition:A soft, white limestone composed mainly of calcium carbonate, formed from the shells of microscopic plankton.