Jasper

Physical Properties

Hardness: 6.5–7 on Mohs scale. Color: Opaque dark green with some tan/brown matrix. Luster: Dull to waxy when unpolished. Crystal system: Trigonal (microcrystalline/cryptocrystalline). Specific Gravity: 2.58–2.91. Cleavage: None, exhibits conchoidal fracture.

Formation & Geological History

Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments. Over time, the silica crystallizes into microcrystalline quartz. Dark green varieties often get their color from iron silicates or chlorite inclusion.

Uses & Applications

Used primarily as an ornamental stone, lapidary work (cabs and tumbling), jewelry (beads and pendants), and as a collector's specimen.

Geological Facts

Jasper has been used as a gemstone since antiquity; it was known in ancient Mesopotamian, Greek, and Egyptian cultures. Because of its hardness, it was also used by early humans to create various tools and scrapers.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass and steel), smooth conchoidal fracture, and complete opacity even when held to a thin light. Often found in stream beds or coastal gravels.

Identified on: 4/22/2026

Mode: Standard