Jasper

Physical Properties

Hardness: 6.5–7 on Mohs scale; Color: Red with black inclusions/bands; Luster: Vitreous to waxy; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None/Conchoidal fracture; Specific gravity: 2.58–2.91.

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, with iron oxides (hematite) providing the red color and manganese or other minerals creating black bands or spots. Found in diverse geological environments from Precambrian to recent ages.

Uses & Applications

Used primarily for jewelry (cabochons, beads), lapidary art, decorative carvings, and as a collector's gemstone. Historically used for making tools due to its hardness and sharp edges when fractured.

Geological Facts

Jasper is an opaque variety of chalcedony. The red color in this specimen is likely due to hematite. Some cultures believed Jasper could provide strength and protection during physical battle.

Field Identification & Locations

Identify in the field by its hardness (will scratch glass), opaque nature, and characteristic conchoidal fracture. Commonly found in riverbeds, glacial tills of the Great Lakes region (like the Mary Ellen Jasper of Minnesota), and arid desert environments.

Identified on: 4/28/2026

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