mineral

Chalcedony (Agate/Opal hybrid)

Microcrystalline Quartz (SiO2) with potential amorphous silica (SiO2·nH2O)

Hardness: 6.5-7 (Mohs); Color: Waxy white, lavender-grey, to pale orange; Luster: Waxy to vitreous; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Translucency: Semi-transparent to translucent.

Hardness: 6
Color: Waxy white, lavender-grey, to pale orange
Luster: Waxy to vitreous

Identified July 8, 2026More mineral →

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Physical properties

Formation & geological history

Formed by the deposition of silica-rich fluids in cavities of volcanic rocks. The regional coordinates (Hidalgo/Querétaro, Mexico) are famous for Tertiary-age volcanic regions rich in silica minerals.

Uses & applications

Commonly used for lapidary work, jewelry (cabochons), and as a collector's specimen. In higher grades, it may be classified as Fire Opal if it displays play-of-color.

Geological facts

This specimen displays a waxy luster and botryoidal-like external texture characteristic of the silica minerals found in central Mexico. It is geologically related to the famous Mexican Fire Opal deposits found in the Trans-Mexican Volcanic Belt.

Field identification & locations

Identify in the field by its waxy appearance, conchoidal fracture, and inability to be scratched by a steel knife. It is extremely common in the volcanic highlands of central Mexico.

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