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Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown

Magnetite

An iron oxide mineral species with formula Fe3O4; it is magnetic, and magnetic beads on the market are often made of man-made magnetite. This page compares how the major standards and institutions name it, what must be disclosed when selling it, whether it can be worn every day, how it is treated and identified, and which source each conclusion comes from.

Price, rarity and origin are outside the scope of this wiki.

Edited by JuneReviewed by RalphLast updated 2026-10-12Who maintains this page

What this page can answer

This page covers

What we cannot conclude

  • Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.
  • Geographic origin, unless an origin report accompanies the item.
  • Price, rarity or investment value: this wiki covers naming and disclosure only.

Material research: formation, causes and history

What authoritative sources say about how this material forms, what causes its colour and optical effects, where its name comes from and how people have used it. Each statement carries an evidence grade and its sources; it describes the material in general, not any specific piece.

How it forms

Magnetite is an iron oxide of formula Fe3O4 (Fe2+Fe3+2O4); it belongs to the spinel group and is strongly magnetic. It is a widespread accessory phase within igneous and metamorphic rocks, where magmatic segregation or contact metamorphism can generate economic deposits, and extensive deposits lie in sedimentary banded iron formations; it may also be biogenic and forms important detrital deposits. Magnetite makes two series, one with jacobsite and one with magnesioferrite, and its strong magnetism distinguishes it from hematite (Fe2O3).

Scope: Covers the origin, occurrence, composition and magnetism of natural magnetite as a mineral species; does not address synthetic magnetite or industrial applications of its magnetic materials.

Sources Handbook of Mineralogy

Where it forms

A widespread accessory phase within igneous and metamorphic rocks; magmatic segregation or contact metamorphism can generate economic deposits

Sources Handbook of Mineralogy

Extensive deposits in sedimentary banded iron formations (BIF)

Sources Handbook of Mineralogy

A biogenic product and an important detrital deposit

Sources Handbook of Mineralogy

How it forms, step by step

  1. In igneous and metamorphic environments, iron crystallizes as magnetite with both Fe2+ and Fe3+.

    Sources Handbook of Mineralogy

  2. Magmatic segregation or contact metamorphism can concentrate magnetite into economically significant deposits.

    Sources Handbook of Mineralogy

  3. Magnetite is widespread in sedimentary banded iron formations, can be biogenic, and may form detrital deposits after weathering and transport.

    Sources Handbook of Mineralogy

Link to appearance

Magnetite is black with a black streak and metallic to submetallic luster, sometimes dull; its most distinctive feature is its strong magnetism. Crystals are typically octahedral, less commonly dodecahedral, and also skeletal, granular, or massive, commonly twinned on the spinel law.

Sources Handbook of Mineralogy

Timescale

The source states no absolute geological timescale for magnetite formation.

Sources Handbook of Mineralogy

Supporting findings

Magnetite is a widespread accessory phase within igneous and metamorphic rocks, where magmatic segregation or contact metamorphism can generate economic deposits; it is abundant in sedimentary banded iron formations and may be biogenic or form an important detrital deposit.

Evidence grade B

Scope: Describes magnetite's occurrence and host environments.

Sources Handbook of Mineralogy

Recorded localities

Authoritative sources list the localities below; the list is not exhaustive.

Locality sketch mapLand outlines only; the map does not depict any national or regional boundary. Dots mark approximate positions. Base map: Natural Earth (public domain).

Europe

North America

South America

Seas and coasts

These are localities recorded by authoritative sources, not an origin finding for any individual piece. The CIBJO Gemstone Book (2022, §4.2.3) says a place of origin names where a gem was mined or harvested, is a matter of opinion, does not imply a level of quality, and that cutting, processing or exporting centres must not be used to imply origin. See how far testing can go on this page, the origin determination guide and the overview of recorded localities.

Where the name comes from

Magnetite is an old name, perhaps alluding to the Magnesia district of Greece. The same sources also give hematite's Greek-derived name, meaning "blood", a reference to its colour.

Evidence grade B

Scope: This states only the origin of the name and does not establish the material's composition, locality, natural origin, or whether it was treated.

Sources Handbook of Mineralogy

Other research findings

Magnetite has the formula Fe3O4 (containing both FeO and Fe2O3), belongs to the spinel group, and forms two series, with jacobsite and with magnesioferrite.

Evidence grade B

Scope: Concerns magnetite's composition and group.

Sources Handbook of Mineralogy

Magnetite is strongly magnetic, an important physical property distinguishing it from other iron oxides.

Evidence grade B

Scope: Describes magnetite's magnetic physical property.

Sources Handbook of Mineralogy

Magnetite (Fe3O4, spinel group) and hematite (Fe2O3, hematite group) are both iron oxides but are distinct mineral species and must not be conflated.

Evidence grade B

Scope: Defines the species boundary between magnetite and hematite.

Sources Handbook of Mineralogy

Limits of this research

  • Research status: Formation, occurrence or other material-specific findings found in authoritative sources
  • The source states no absolute age or specific P-T conditions for magnetite formation.

Methodology

Evidence grades

A
Standards bodies, government geological surveys, peer-reviewed research and museum records
B
Institutional educational material
C
Specialist databases or cautious readings

A statement is never graded above its strongest source.

This section is LumaLark's own factual restatement of public authoritative sources, credited item by item; it contains no verbatim excerpts, images or third-party logos.

DecideListing name, disclosure, care and treatments

Suggested listing name
Magnetite

GB/T 16552—2017 5.1.1 b) · CIBJO Gemmological Laboratories Book 2024 §7.2.1.136 “Magnetite”

Construction or treatment status

Natural identity; treatment status unknown

This page cannot answer

Natural? · Origin · Price

A lab report settles these; this wiki covers naming and disclosure.

Related:What this page can answer

Answer at a glance

Magnetite is Magnetite (Fe3O4); use "Magnetite" for listings, and disclose any known treatments.

What this means for you

Before buying, check the recommended listing name "Magnetite" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.

Last reviewed
2026-09-01

Care and wear

No institutional care guidance is registered for this material yet; below are its durability indicators and general guidance.

Durability and wearing

Numbers in curly braces, such as {111}, are crystallographic face symbols (Miller indices): each marks a set of crystal faces or cleavage planes. They are reproduced as written in the cited source.

Mohs hardness

5.5–6.5

Toughness

Brittle

Cleavage

Parting on {111}, very good

Fracture

Uneven

Sources Handbook of Mineralogy

Daily wear

Magnetite ranks 5.5–6.5 on the Mohs scale and is brittle with a very good {111} parting; daily wear should avoid impacts that may split it.

Care

As a brittle material with cleavage, clean gently with warm, mild soapy water and a soft cloth; avoid ultrasonic and steam cleaners, sudden temperature changes, and impact or rubbing against hard objects.

General guidance: LumaLark's general guidance inferred from the material's properties (hardness, toughness, cleavage); not text from the cited source, and not a guarantee for any specific piece.

Scope: This field describes the general properties of the material and does not constitute a durability or safety guarantee for any specific finished product; the durability of treated (filled/dyed/coated) or composite pieces must be assessed separately.

VerifyNames, standards, technical facts, clauses and sources

Names

Standard and listing namesThe suggested listing name for Magnetite is Magnetite. GB/T 16552—2017 Annex A does not list this name, but under the GB/T 16552—2017 naming rules, mineral, rock and material names not included in Annex A can be used directly; the mineralogical name is Magnetite (Fe3O4). Names in four languagesNames are given in Simplified Chinese, Traditional Chinese, English (Magnetite) and Japanese, and the GSJ (Japan) formal name is the Japanese term for magnetite. Institution usageOn institutional wording, CIBJO's Gemmological Laboratories Book 2024 includes Magnetite; the FTC text contains no wording for this name (checked); GIA and Gem-A are unchecked. Bodies without a recorded wording show the entry's own English name, which does not represent their position.

Authority wording

GIA, FTC, CIBJO, Gem-A
Magnetite (on record for CIBJO (CIBJO Gemmological Laboratories Book 2024 §7.2.1.136); no wording for this name in the FTC text on file; GIA, Gem-A unchecked — bodies without a recorded wording show the entry's own English name)
GSJ (Japan) formal name
磁鉄鉱
Mineral / material name (not in GB/T 16552 Annex A; usable directly)
磁铁矿 (GB/T 16552—2017 §5.1.1 b))
Mineralogical name
Magnetite (Fe3O4)

Four-language names

简体中文
磁铁矿
繁體中文
磁鐵礦
English
Magnetite
日本語
マグネタイト／磁鉄鉱

See also: Misleading and prohibited trade names · Supplementary name index

Classification

Origin
Natural materials
Material domain
Natural inorganic gem materials
Browsing family
Oxide minerals
Identity tier
Mineral species
Mineral chemical class
Oxides / hydroxides
Construction or treatment status
Natural identity; treatment status unknown

What it is and how it's identified

The registered material facts for Magnetite are: nomenclature status IMA status G, meaning grandfathered, described before the IMA existed and generally regarded as a valid mineral species; composition (phase) registered as magnetite, of the spinel group. Optically, transparency is opaque, and body colour, untreated, is black. This site also notes that in the CIBJO Gemmological Laboratories Book the colour descriptions for entries such as melanite, schorl and jet also mention black or blackish colours.

Registered material facts

Each row carries its own source and check date and can be cited on its own; “—” means the cited source gives no value, not “none”.

Definition

Magnetite — nomenclature status: IMA status G: grandfathered (described before the IMA existed, and generally regarded as a valid species).

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Magnetite — composition (phase): magnetite (spinel group)

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Optical

Magnetite — transparency: opaque.

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Magnetite — body colour: black.

CIBJO Gemmological Laboratories Book 2024

Treatment state
untreated
Qualification

In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Melanite, Black Tourmaline, Jet and other entries also name black or a blackish colour.

General note
colour alone is not identity
Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Each row's “Source & check” expands to the full source; the date beside it is the fact check date.

Testing and market

A synthetic counterpart of Magnetite exists on the market. The CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) lists it as Magnetite and records that a synthetic counterpart of Magnetite is available on the market, for any treatment state.

How far testing can go

Magnetite — synthetic counterpart on the market: A synthetic counterpart of this material is commercially available

CIBJO Gemstone Book 2022

Treatment state
any treatment state
Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Each row's “Source & check” expands to the full source; the date beside it is the fact check date.

Clause-level definitions

Magnetite is listed in the CIBJO Gemmological Laboratories Book 2024 under the term Magnetite, defined as black and opaque; the cross-check result is that it is defined directly by CIBJO, and no identically named English entry was found in the GB/T annex. In the IMA mineral list, Magnetite is recorded as Magnetite Fe2+Fe3+2O4 G 1845 and is cross-checked against the main table of the RRUFF/IMA mineral list, which is public-domain data.

This table scrolls sideways on narrow screens.

TermClauseDefinitionCross-check
Magnetite7.2.1.136black, opaqueDefined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex.
MagnetiteIMA Mineral List entryMagnetite Fe2+Fe3+2O4 G 1845Cross-checked against the RRUFF/IMA master mineral list (public domain data).

Evidence and sources

Authority basis and clause sources

GB/T 16552—2017
Not listed the name does not occur anywhere in the text; scope: Chapter 1 “Scope” · Source
GB/T 16552—2017
Naming rule 5.1.1 b) · Source
CIBJO Gemmological Laboratories Book 2024
Listed §7.2.1.136 “Magnetite” · Source
IMA Mineral List 2026-07
Listed “Magnetite” · Source

Sources

Further reading

Related entries and topic cluster

Parent entry and related pages on this site. Rows marked “Planned” are suggested new content and have no link yet.

This table scrolls sideways on narrow screens.

PageContentStatus
Browsing familyOxide mineralsLive
Related articlesTo be added (placeholder)Planned

Who maintains this page

The material facts in the Magnetite entry are maintained by the LumaLark wiki and matched one by one to the standard clauses or institutional sources they cite: every fact carries its source (with a clause or page locator) and a check date, so it can be traced back to the original; clause-level definitions also carry a cross-check result. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.

Facts editor
June
Reviewer
Ralph
How facts are checked
Each fact is matched to the clause it cites; facts checked on 2026-09-22
Last revised
2026-10-12
Purpose
Lets buyers and sellers check naming, disclosure and material facts clause by clause.

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