Jasper

Physical Properties

Hardness: 6.5-7 (Mohs); Color: Reddish-brown (due to iron inclusions); Luster: Vitreous to dull; Crystal structure: Microcrystalline/Cryptocrystalline (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91.

Formation & Geological History

Formed through the deposition of silica from water-rich solutions into minerals or volcanic ash during sedimentary processes. The red color is typically caused by the oxidation of iron (hematite) during formation in hydrothermal or sedimentary environments.

Uses & Applications

Commonly used in jewelry (cabochons, beads), decorative lapidary arts, and as a collector's mineral. Historically used for making tools due to its conchoidal fracture.

Geological Facts

Jasper is an opaque variety of chalcedony. It has been used for seals and amulets since ancient Mesopotamian and Greek civilizations and is mentioned in many historical and religious texts as a precious stone.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass), opaque nature (unlike translucent carnelian), and smooth, shell-like (conchoidal) fracture surface. Frequently found in gravel beds or as nodules in volcanic rocks.

Identified on: 4/27/2026

Mode: Standard