mineral
Tumbled yellow jasper (likely iron-stained chalcedony)
Jasper, microcrystalline quartz (SiO₂) with iron-oxide inclusions
AI-generated identification · may be incorrectOpaque mustard-yellow to ochre, earthy/waxy luster, fine-grained and noncrystalline to the naked eye; Mohs hardness about 6.5–7, no cleavage, specific gravity roughly 2.6. The rounded shape indicates tumbling or natural abrasion.
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Physical properties
Opaque mustard-yellow to ochre, earthy/waxy luster, fine-grained and noncrystalline to the naked eye; Mohs hardness about 6.5–7, no cleavage, specific gravity roughly 2.6. The rounded shape indicates tumbling or natural abrasion.
Formation & geological history
Forms when silica-rich groundwater replaces or fills cavities in volcanic or sedimentary rocks, with iron oxides producing the yellow color; deposits range from Precambrian to recent ages. Exact locality cannot be determined from the image.
Uses & applications
Used for cabochons, beads, carvings, ornamental objects, and inexpensive polished specimens; it has little industrial value compared with ordinary quartz.
Geological facts
Jasper is a variety of opaque chalcedony, often grouped commercially by color or locality rather than as a distinct mineral species. Yellow coloration commonly reflects limonite or goethite.
Field identification & locations
Identify by its opaque color, fine texture, glass-scratching hardness, and lack of visible grains or cleavage; common sources include Brazil, India, Madagascar, the western United States, and Australia.
