mineral

Chalcedony (agate variety)

Microcrystalline quartz, SiO₂; agate is banded chalcedony

AI-generated identification · may be incorrect

Translucent gray-lavender material with brown staining and a waxy to vitreous luster; quartz crystal structure, Mohs hardness 6.5–7, no cleavage, specific gravity about 2.6. The rough, irregular edges suggest a broken or sawn piece rather than a finished gem.

Identified October 8, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited microscopic quartz fibers in cavities or fractures, commonly in volcanic rocks; iron-bearing impurities can create brown coloration. Chalcedony forms across many geological ages.

Uses & applications

Used for beads, cabochons, carvings, and decorative objects; agate is also collected as a lapidary material.

Geological facts

Chalcedony’s crystals are too small to distinguish individually without magnification; visible banding is characteristic of agate, but is not clear in this specimen.

Field identification & locations

Look for waxy luster, translucency, hardness near 7, and conchoidal fracture; common sources include Brazil, Uruguay, India, and the western United States. The image alone does not establish a precise variety.