sedimentary

Jasper

Silicon Dioxide (SiO2) - Impure Variety of Chert

Hardness: 6.5-7 (Mohs scale); Color: Red (due to iron inclusions), brown, yellow; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.58-2.91

Hardness: 6
Color: Red (due to iron inclusions), brown, yellow
Luster: Vitreous to greasy

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Jasper forms when fine silicate materials or volcanic ash are deposited. Over time, heat and pressure transform these into a compact, cryptocrystalline variety of quartz. Red jasper specifically gains its color from the oxidation of iron within the silica during formation.

Uses & applications

Predominantly used as a gemstone for jewelry, lapidary art, and ornamental carvings. Historically used for making tools like scrapers and arrowheads due to its conchoidal fracturing.

Geological facts

In antiquity, Jasper was known as the 'supreme nurturer.' It has been found in archaeological sites dating back to the Neolithic period and was a favorite stone in the ancient world for seals and amulets.

Field identification & locations

Identify in the field by its opaque nature (unlike translucent carnelian), its high hardness (it will scratch glass), and its distinctive smooth, waxy feel. It is commonly found in riverbeds or volcanic regions globally, notably in India, Brazil, and the USA.

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