Red Jasper (Chert)

Physical Properties

Hardness: 6.5-7 (Mohs scale); Color: Brick red to brownish-red; Luster: Dull to vitreous; Crystal Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Formation & Geological History

Formed from silica-rich fluids that permeate through volcanic ash or sedimentary beds, often during the late stages of igneous activity. Its age can range from hundreds of millions to billions of years depending on the deposit.

Uses & Applications

Commonly used as a gemstone for lapidary work, jewelry, ornamental items, and historically for tools like scrapers or arrowheads due to its sharp conchoidal fracture.

Geological Facts

Jasper is an opaque variety of chalcedony. The red color is caused by the presence of iron (hematite) inclusions within the cryptocrystalline quartz structure. In ancient times, it was known as the 'rain bringer' by Native Americans.

Field Identification & Locations

Identify in the field by its opacity (even on thin edges), its characteristic 'waxy' to dull luster, and red streak. It is commonly found in gravel pits, riverbeds, and as nodules in many geological formations worldwide.

Identified on: 4/13/2026

Mode: Standard