mineral

Tumbled quartz-rich agate/geode fragment

Microcrystalline quartz (SiO₂), likely chalcedony with crystalline quartz and possible iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent gray-white to honey-brown, with a vitreous to waxy luster and irregular internal cavity. Quartz is trigonal; chalcedony is fibrous microcrystalline quartz, with no prominent cleavage and specific gravity about 2.6.

Identified August 9, 2026More mineral →

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At a glance

Common name: Tumbled quartz-rich agate/geode fragment
Scientific name: Microcrystalline quartz (SiO₂), likely chalcedony with crystalline quartz and possible iron-oxide inclusions
Category: mineral
Identified: August 9, 2026
Method: Standard

AI Estimated Value

About $3–$15 for a common tumbled specimen; $20–$75 if unusually attractive, crystalline, or locality-labeled.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony and later quartz crystals; iron oxides create the brown coloration. The specimen is likely Cenozoic or younger, though exact age and locality cannot be determined from the image.

Uses & applications

Used as a decorative tumbled stone, lapidary material, cabochon, and collectible; quartz-rich agate has modest jewelry and ornamental value.

Geological facts

The hollow, sparkly interior suggests a small geode or vug rather than uniformly banded agate. Surface polishing enhances translucency and reveals the quartz-filled cavity.

Field identification & locations

Identify by its waxy chalcedony body, glassy quartz patches, hardness, and lack of cleavage; common sources include Brazil, Uruguay, Mexico, Madagascar, and the United States.