Chert (likely jasper/chalcedony-rich chert)

Hardness 6.5–7 Mohs; reddish-brown to gray, waxy or dull luster, opaque to slightly translucent edges, and no visible cleavage. It breaks with smooth conchoidal fractures and has a dense, fine-grained texture.

Forms when silica-rich groundwater replaces or precipitates within sediments, commonly from radiolarian or carbonate-rich deposits; ages range from Precambrian to recent. The red color generally comes from iron oxides.

Used historically for flint tools and arrowheads, and today for carvings, lapidary objects, decorative stone, and occasional jewelry. It is not usually used as a major construction aggregate.

The sharp conchoidal edge is characteristic of chert and made it valuable for prehistoric cutting tools. The specimen may be specifically called red jasper if its coloration and opacity are dominant.

Identify it by its glassy-conchoidal fracture, very high hardness, fine texture, and inability to scratch with a steel knife; quartz-rich chert commonly occurs as nodules or layers in limestone and other sedimentary rocks. Common sources include the United States, Mexico, India, Australia, and Europe.