Rock Identifier
Orange chalcedony / agate fragment (Microcrystalline quartz (SiO₂), likely iron-stained chalcedony) — mineral
mineral

Orange chalcedony / agate fragment

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, vitreous to waxy luster, translucent orange-brown color, conchoidal fracture, and no cleavage; the granular appearance may indicate agate or quartz-rich material.

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Physical properties

Typically Mohs hardness 6.5–7, vitreous to waxy luster, translucent orange-brown color, conchoidal fracture, and no cleavage; the granular appearance may indicate agate or quartz-rich material.

Formation & geological history

Forms when silica-rich fluids fill cavities and fractures in volcanic rocks, commonly developing layered or botryoidal chalcedony; iron oxides produce the orange coloration. Most specimens formed in relatively young volcanic environments, though exact age is indeterminate from the image.

Uses & applications

Used as a lapidary stone for cabochons, beads, carvings, and decorative objects; attractive pieces have modest jewelry and collecting value.

Geological facts

Agate is technically banded chalcedony, while unbanded orange material is generally called orange chalcedony or carnelian. The visible rough, irregular texture is consistent with a broken or weathered fragment.

Field identification & locations

Commonly found in basaltic volcanic regions, including Brazil, Uruguay, India, Madagascar, Mexico, and the western United States. A glassy fracture, hardness sufficient to scratch ordinary steel, and lack of fizz in dilute acid support quartz identification.