mineral

Common opal in iron-stained host rock

Opal (hydrated amorphous silica, SiO₂·nH₂O), likely common opal

AI-generated identification · may be incorrect

Creamy white to yellow material with brown iron-oxide staining and dark inclusions, set in a reddish-brown matrix. Opal has no crystal structure, Mohs hardness about 5.5–6.5, and a vitreous to waxy luster; the image does not show clear play-of-color.

Identified September 30, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich water deposited gel-like silica in cavities or fractures, later hardening into opal; iron oxides colored the surrounding material. Exact age and locality cannot be determined from the image.

Uses & applications

Used as a decorative or lapidary material when attractive; this specimen appears more suitable for collecting or display than fine jewelry.

Geological facts

Opal is mineraloid rather than a crystalline mineral. Dark specks may be iron or manganese oxides, though the image alone cannot confirm their identity.

Field identification & locations

Look for waxy luster, irregular fracture, and cream-colored silica against iron-stained rock; opal occurs worldwide in volcanic and sedimentary settings. The visible piece is rough and lacks obvious precious-opal color play.