Lodestone Identification Guide

What Lodestone Looks Like

Lodestone is a naturally magnetized piece of the mineral magnetite (an iron oxide) that acts as a permanent magnet — it attracts iron and can pick up iron filings, paperclips, and other small steel objects. It is the only naturally occurring permanent magnet and was historically used as an early compass. Visually it looks like ordinary magnetite: a dark, heavy, metallic-to-submetallic rock, but its behavior is what defines it.

• Color: black to brownish-black
• Luster: metallic to submetallic
• Transparency: opaque
• Habit: massive, granular, sometimes with octahedral magnetite crystal faces
• Telltale trait: clings to iron and lifts iron filings without any external magnet

Step-by-Step Field-ID Checklist

1. Test for natural magnetism. Bring it near steel paperclips, iron filings, or a compass needle. Lodestone will attract them and may pick them up on its own — this is the defining test.
2. Check that it attracts a magnet AND attracts iron unaided. Plain magnetite is attracted to a magnet; true lodestone is itself magnetic and picks up iron filings.
3. Do the streak test. Magnetite leaves a black streak on unglazed porcelain.
4. Heft it. It is notably heavy (high density) for its size.
5. Test hardness. It scratches glass (Mohs ~5.5–6.5).

Key Diagnostic Tests

• Magnetism: strong, permanent, natural magnetism — the diagnostic property. It deflects a compass and picks up iron filings unaided.
• Streak: black.
• Mohs hardness: about 5.5–6.5; scratches glass.
• Specific gravity: high, around 5.0–5.2 — feels heavy.
• Cleavage: none; uneven to conchoidal fracture (parting along octahedral planes possible).
• Acid: essentially no reaction.

Common Look-Alikes and How to Tell Them Apart

• Ordinary magnetite: chemically identical, but plain magnetite is only attracted to magnets — it does not itself pick up iron filings. If it lifts filings on its own, it is lodestone.
• Hematite: can be black and metallic but gives a red-brown streak and is only weakly magnetic at most (some specular hematite); the streak test separates them.
• Ilmenite: dark, metallic, weakly magnetic, with a black-to-brownish streak; far less magnetic than lodestone and usually associated with different settings.
• Chromite: dark and heavy but brown streak and only weakly magnetic.
• Pyrrhotite: brassy-bronze, magnetic to a degree, but has a metallic bronze color and dark streak — color separates it.
• Man-made magnets/slag: check for natural rock texture; magnetic slag may attract iron but usually shows a glassy, vesicular, artificial appearance.

Where It Is Typically Found

Lodestone is found in magnetite-rich deposits, particularly where rocks have been struck by lightning or experienced strong natural magnetic fields that aligned the magnetite's domains. It occurs in iron ore bodies, banded iron formations, and metamorphic and igneous rocks bearing abundant magnetite, in iron-mining regions worldwide. Only a small fraction of magnetite is actually magnetized into lodestone, so genuine specimens are relatively uncommon.