mineral

Tumbled dark blue-green stone, likely blue apatite or indigo gabbro

Apatite, Ca5(PO4)3(F,Cl,OH), or possibly quartz-rich indigo gabbro

AI-generated identification · may be incorrect

Polished/tumbled, dark blue-green to gray with reflective granular patches; likely Mohs 5 (apatite) or 6–7 if gabbro/quartz-bearing. Vitreous to subvitreous luster; exact cleavage, crystal structure, and specific gravity require testing.

Identified September 3, 2026More mineral →

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At a glance

Common name: Tumbled dark blue-green stone, likely blue apatite or indigo gabbro
Scientific name: Apatite, Ca5(PO4)3(F,Cl,OH), or possibly quartz-rich indigo gabbro
Category: mineral
Identified: September 3, 2026
Method: Standard

AI Estimated Value

Approximately $3–$20 for a common tumbled specimen; unusual transparent blue apatite or verified rare material may sell for $25–$100+.

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

If apatite, it crystallized in igneous or metamorphic rocks during geologic time, commonly in granitic pegmatites; if gabbro, it formed by slow cooling of mafic magma. The photograph alone cannot establish age or locality.

Uses & applications

Used mainly as a lapidary or collector stone; apatite may be used as a phosphate source, while gabbro is used as crushed stone or dimension stone. This specimen appears tumbled rather than jewelry-grade faceted material.

Geological facts

The intense dark color and metallic-looking inclusions are not diagnostic and may reflect surface polish, inclusions, or a coating. A streak, hardness, specific-gravity, and magnification test would substantially improve identification.

Field identification & locations

Check whether it scratches glass (about Mohs 5.5), examine grain boundaries under magnification, and test streak on unglazed porcelain; avoid destructive tests until coating is excluded. Blue apatite commonly occurs in Brazil, Madagascar, Mexico, and Canada.