hematite
Enable an agent to recognise hematite, assess the composition and condition of a specimen or material lot, and determine its suitability for a proposed use.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise hematite, assess the composition and condition of a specimen or material lot, and determine its suitability for a proposed use.
Hematite is the mineral form of alpha iron(III) oxide, α-Fe₂O₃, with the corundum crystal structure, distinguished by its reddish-brown streak and important as an iron ore.
It can be Identify a candidate specimen using streak and appearance, then select phase analysis where greater confidence is required.; Classify a sample as hematite, hematite-rich material or a mixture with a measured hematite fraction.; Compare a characterised lot with documented requirements for pigment, iron feedstock, research or specimen use.; Select further tests to explain unexpected magnetism, colour or composition.; Determine handling controls from particle form, impurities and applicable material documentation.; Track treatment or storage changes and reassess whether the material remains hematite and retains its intended grade..
Distinguishing features
Confirm an α-Fe2O3 diffraction pattern when phase identity matters; iron and oxygen measurements alone cannot distinguish hematite from other iron oxides.
Check for a characteristic red to reddish-brown streak even when the specimen surface appears metallic grey or black; surface colour alone is insufficient.
Use magnetic response as a screening observation: strong attraction warrants investigation for magnetite or another magnetic component rather than automatic rejection or acceptance as hematite.
Distinguish hematite from iron oxyhydroxides such as goethite through phase analysis rather than treating all rusty red or brown materials as the same substance.
Verify mineral identity independently of trade names, especially for polished or strongly magnetic products sold as hematite.
Scope
+ Mineral and crystalline-phase identity of hematite
+ Hematite abundance, chemical purity, substitutions and associated minerals
+ Crystal habit, particle size, surface condition and physical properties
+ Formation or manufacturing provenance and subsequent alteration
+ Evidence supporting identification, handling and use suitability
- Whole ore deposits, resource estimates and mining operations
- Magnetite, maghemite, goethite and other separately identifiable mineral phases
- Finished paints, ceramics, jewellery and other products containing hematite
- Complete ironmaking, beneficiation or pigment-manufacturing processes
- Clinical conditions or biological iron metabolism
Characteristics
- Crystalline-phase identity
- α-Fe2O3 confirmed; provisional hematite identification; mixed phases; unresolved Defines whether the material is hematite rather than another iron oxide or a lookalike.
- Hematite phase fraction
- Mass %, with analytical method, uncertainty and detection limits Separates a hematite specimen or powder from an ore or mixture merely containing hematite.
- Chemical composition and impurities
- Elemental mass % or mg/kg, specifying dry or as-received basis Constrains processing behaviour, grade and contaminant-related handling requirements.
- Associated mineral phases
- Identified phases, estimated abundance and spatial association Gangue, intergrowths and magnetic inclusions can dominate observations and use suitability.
- Habit and material form
- Platy or specular; earthy; massive; botryoidal; discrete crystals; manufactured powder; other documented form Connects mineral identity to sampling, handling and interpretation of appearance.
- Streak and appearance
- Observed streak colour, surface colour and lustre under recorded conditions Supports field identification while keeping surface appearance separate from diagnostic evidence.
- Particle size distribution
- µm or mm, with method and distinction between primary particles and agglomerates Affects dust generation, pigment behaviour and processing response.
- Magnetic response
- Qualitative attraction or quantified susceptibility or magnetisation, with units, temperature and applied field Helps investigate phase mixtures and assess magnetic separation assumptions.
- Density and porosity
- Density in g/cm³ and porosity in %, distinguishing grain, apparent and bulk measurements Prevents packing or pore effects from being mistaken for changes in mineral identity.
- Surface treatment and alteration
- Untreated; coated; weathered; thermally treated; partially transformed; unknown Explains changes in appearance, reactivity and suitability that bulk composition may miss.
- Substance and lot identification
- Verified mineral reference, applicable CAS or EC identity, supplier lot and safety data sheet Links the actual material to traceable records without assuming that a broad iron oxide identifier establishes its crystalline phase.
Also called
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 5 bundles · 9 layers · 16 findings · 24 questions.
Hematite identity Establishes whether the named material contains the hematite crystalline phase and how securely that identity is known.
Iron oxide chemistry, colour and commercial naming can each conceal a different phase or a mixture.
Phase confirmation
Separates mineral identity from elemental composition.
Evidence for α-Fe2O3
Record the analytical basis for assigning hematite and the limitations of that assignment.
- What diffraction or other phase-sensitive evidence identifies α-Fe2O3 in this material? measurement
- Could the available method miss maghemite, magnetite, poorly crystalline material or a minor mixed phase? boundary
Field and trade identification
Uses accessible observations while testing labels and common confusions.
Streak, appearance and magnetism
Record observations together so that one attractive but ambiguous feature does not determine identity.
- Does a representative uncoated portion produce a red to reddish-brown streak, and how was the test performed? measurement
- If the material is strongly magnetic or sold under a hematite trade name, what evidence excludes a substitute or magnetic inclusion? boundary
Composition and mineral association Determines how much hematite is present and what accompanies it.
A nominally hematite material can behave as an ore, composite or contaminated powder rather than a pure mineral.
Phase and chemical purity
Keeps mineral abundance distinct from bulk iron content.
Basis of purity claims
Require measurements that distinguish hematite fraction, total iron and reported iron oxide equivalents.
- What are the measured hematite phase fraction and total iron content, and on what moisture basis are they reported? measurement
- Does a reported Fe2O3 percentage represent directly identified hematite or an oxide-equivalent calculation from bulk chemistry? definition
Impurities and intergrowths
Locates constituents that affect interpretation, separation or acceptability.
Location of non-hematite constituents
Distinguish lattice-associated elements from separate grains, inclusions and surface contamination.
- Which associated minerals and trace elements are detected, at what concentrations and detection limits? measurement
- Are unwanted constituents incorporated within hematite, intergrown with it or present as separable grains or coatings? boundary
Physical form and history Connects hematite's morphology and measured behaviour to its origin and treatment.
Earthy hematite, specular crystals and synthetic powders share phase identity while presenting different sampling and use constraints.
Morphology and properties
Characterises the actual specimen or lot rather than substituting ideal mineral constants.
Form-dependent behaviour
Record particle structure and physical measurements with methods that make comparisons meaningful.
- What crystal habit, particle size distribution, agglomeration and porosity describe the material? measurement
- Under what methods and conditions were density, magnetic response and colour measured? measurement
Origin and transformation
Tracks natural formation, synthesis and subsequent changes relevant to present identity.
Formation and treatment history
Link provenance and processing records to observed coatings, textures and phase changes.
- What locality or synthesis route, precursor and treatment history are documented for this hematite? provenance
- What evidence shows whether heating, reducing conditions, weathering or surface treatment changed its phase composition or surface state? measurement
Use and handling decisions Translates characterised hematite properties into bounded decisions about use and handling.
Mineral identity alone does not establish pigment performance, iron-feed suitability or appropriate dust controls.
Grade and use fit
Evaluates a specific lot against an explicit intended use.
Application acceptance criteria
Connect each suitability judgement to measurements and requirements relevant to that application.
- For the intended pigment, iron-feed, research or specimen use, which limits apply to phase purity, impurities, particle size and colour? action
- Which representative lot measurements demonstrate compliance, and which unmet criteria require testing or treatment? measurement
Material-specific handling
Resolves identity documentation and exposure considerations for the material as supplied and used.
Dust and substance documentation
Assess powder exposure and associated constituents using applicable records rather than inferring safety from the mineral name.
- Which verified substance identifiers, safety data sheet and jurisdiction-specific classifications apply to this exact material? provenance
- Will the proposed operation generate airborne dust, and what controls follow from particle size, measured contaminants and applicable exposure limits? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This is recall-based information; no sources were consulted.
- The listed varieties describe habit, texture or replacement history rather than separate mineral species.
- Grade-specific identifiers, hazard classifications, exposure limits and thermal behaviour require verification; bulk ore properties differ from those of pure crystals.
- Which of these check these first hold for the sense of hematite this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Specular hematite: metallic, reflective crystals or aggregates
- Micaceous hematite: thin, platy crystals
- Earthy hematite: fine-grained, commonly red material
- Botryoidal hematite: rounded, grape-like aggregates
- Martite: hematite pseudomorphs after magnetite
- Which of these kinds and varieties hold for the sense of hematite this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- Chemical formula - α-Fe₂O₃ - The alpha designation distinguishes hematite from other iron(III) oxide structures.
- CAS Registry Number - 1309-37-1 - Identifies iron(III) oxide; alone it does not establish hematite phase identity, mineral purity or commercial grade.
- Which of these identifiers and schemes hold for the sense of hematite this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Iron ore for iron and steel production
- Red pigment in paints, ceramics and construction materials
- Platy micaceous iron oxide pigment in protective coatings
- Iron oxide polishing powders, including jeweller's rouge
- Dense aggregate or weighting material where suitable grade and purity are available
- Which of these real-world use hold for the sense of hematite this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Density of compact, relatively pure material - Approximately 5.2-5.3 - g/cm³
- Mohs hardness of coherent crystals - 5-6.5 - Mohs scale
- Theoretical iron mass fraction in pure Fe₂O₃ - Approximately 69.9 - % by mass
- Streak colour - Red to reddish brown - Not applicable
- Which of these typical measurements hold for the sense of hematite this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Handling, crushing or grinding can generate airborne mineral dust.
- Natural ore can contain silica and other impurities; its hazards cannot be inferred from the hematite formula alone.
- Gangue, moisture and porosity reduce usable iron content or bulk density relative to ideal mineral values.
- Particle size and crystal shape affect pigment colour, polishing behaviour and coating performance.
- Material sold as magnetic hematite may be a manufactured magnetic material rather than natural hematite.
- Which of these failure modes and hazards hold for the sense of hematite this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Ore deposits differ in associated minerals, texture and impurity content, affecting beneficiation and commercial suitability.
- Which of these regional variation hold for the sense of hematite this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Magnetite - Magnetite is Fe₃O₄, usually strongly magnetic with a black streak; hematite is α-Fe₂O₃ with a reddish-brown streak.
- Maghemite - Maghemite is γ-Fe₂O₃ with a different crystal structure and ferrimagnetic behaviour; diffraction distinguishes the phases.
- Goethite - Goethite is the iron oxyhydroxide α-FeO(OH), generally with a yellow-brown streak.
- Iron ore - Iron ore is economically usable iron-bearing material that may contain hematite, other minerals and gangue; hematite is a specific mineral species.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of hematite this model covers, and on what evidence? provenance
What the second pass must settle
- Which authoritative mineral and substance records should anchor hematite identity, and which chemical identifiers cover broader iron(III) oxide forms?
- What analytical combination and detection limits are sufficient to distinguish hematite from maghemite and quantify poorly crystalline or minor phases in the intended samples?
- Which reference property values and temperature or atmosphere conditions should be recorded, including whether a reported thermal endpoint represents melting or a phase-changing reaction?
- Which application-specific standards establish acceptable hematite purity, impurity levels, particle size and pigment performance?
- Which current jurisdiction-specific classifications and exposure limits apply to the actual powder or specimen, including associated silica or other contaminants?