mineral

Polished magnetite-rich ironstone (possible magnetite pebble)

Magnetite, Fe₃O₄; possibly magnetite-bearing basalt or ironstone

AI-generated identification · may be incorrect

Black to dark gray, opaque, metallic-to-submetallic luster, commonly fine-grained and rounded from tumbling; Mohs hardness about 5.5–6.5, relatively dense (specific gravity ~5.2 for pure magnetite), and strongly magnetic. The image alone cannot confirm whether it is pure magnetite or a magnetite-rich rock.

Identified September 5, 2026More mineral →

Explore Polished magnetite-rich ironstone (possible magnetite pebble) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Polished magnetite-rich ironstone (possible magnetite pebble)
Scientific name: Magnetite, Fe₃O₄; possibly magnetite-bearing basalt or ironstone
Category: mineral
Identified: September 5, 2026
Method: Standard

AI Estimated Value

Typically $1–$10 for a small common polished specimen; approximately $10–$30 if unusually magnetic, attractive, or sold as a quality collector piece.

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

Magnetite forms in igneous and metamorphic environments, hydrothermal veins, and sedimentary iron deposits; basaltic source rocks may be hundreds of millions to billions of years old. The smooth shape and shine indicate natural water wear or human polishing.

Uses & applications

Used as iron ore, pigment, dense media, and for magnetic materials; attractive polished pieces are collected but are generally not jewelry gemstones.

Geological facts

Magnetite is one of the most strongly magnetic common minerals and can form naturally magnetized lodestone. Its black streak distinguishes it from many dark silicate rocks.

Field identification & locations

Test with a strong magnet and check for a black streak on unglazed ceramic; unusually high heft supports magnetite. Common sources include iron-ore regions, volcanic terrains, and black-sand beaches.