gemstone

Matrix Opal (Cantera Opal in Rhyolite)

Hydrated Amorphous Silica (SiO2·nH2O) in Rhyolite/Jasper Matrix

AI-generated identification · may be incorrect

Hardness: 5.5 - 6.5 (opal) to 6.5 - 7 (host matrix); Color: Reddish-pink to cream swirl matrix with dark embedded clasts showing vibrant purple, blue, and green play-of-color; Luster: Vitreous to waxy; Specific gravity: ~2.1 - 2.6.

Hardness: 5
Luster: Vitreous to waxy

Identified October 3, 2026More gemstone →

Explore Matrix Opal (Cantera Opal in Rhyolite) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed in volcanic environments where silica-rich hydrothermal fluids seeped into cavities, fractures, or breccias of volcanic rock (such as rhyolite or tuff) and solidified over millions of years into precious and common opal.

Uses & applications

Popular for lapidary arts, decorative carved eggs, cabochons for jewelry, and prized among geological and mineral collectors.

Geological facts

Matrix opal is unique because the precious opal is naturally embedded and left within its host rock, providing a dramatic contrast between the dull volcanic stone and flashes of vivid iridescence (play-of-color).

Field identification & locations

Identified by the distinct contrast of angular or nodular dark inclusions showing iridescence set inside a volcanic or siliceous matrix; famously found in Mexico (such as Jalisco and Querétaro), Honduras, and parts of Australia.