mineral

Amethyst-bearing quartz geode fragment

Quartz, SiO₂; purple coloration from trace iron and irradiation

AI-generated identification · may be incorrect

Coarse drusy crystal lining with pale-to-medium purple amethyst and a whitish quartz/possibly chalcedony rim. Quartz has Mohs hardness 7, vitreous luster, hexagonal crystal structure, no cleavage, and specific gravity about 2.65; the dark greenish outer material may be weathered host rock or coating.

Identified September 15, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater filled a cavity in volcanic rock, depositing quartz and later amethyst crystals. Such growth commonly occurred in Mesozoic volcanic provinces, often millions to over 100 million years ago.

Uses & applications

Used as a decorative and collecting specimen; larger, cleaner crystals may be cut for jewelry. This small, irregular fragment has modest commercial value.

Geological facts

Amethyst’s purple color is commonly caused by iron-related color centers. Heating can turn some amethyst yellow or orange, producing citrine-like material.

Field identification & locations

Identify by glassy purple quartz crystals that scratch glass and are harder than steel. Brazil is a major source; northeastern Brazil is geologically plausible for amethyst, though the precise reported location is insufficient for a confident locality assignment.