Hematite
Hematite is Fe2O3, hardness 5 to 6, density 5.26, crystals to 13 cm. It has no cleavage at all, and the streak is cherry-red whatever colour the specimen is.
Hematite is iron oxide, Fe2O3, hexagonal, hardness 5 to 6 with a measured density of 5.26 and crystals to 13 cm. It has no true cleavage. Whatever the specimen looks like — steel-grey metallic, black micaceous rosettes or red earthy ore — the streak is cherry-red to reddish brown.
In short
- The streak is the whole identification. Hematite gives a cherry-red or reddish-brown streak on unglazed porcelain regardless of how the specimen looks. A steel-grey metallic mass, a black platy rosette and a soft red ochre all streak the same, and nothing else common in a British collection does.
- Hematite has no cleavage. The Handbook of Mineralogy records parting on {0001} and {10-11} caused by twinning, not cleavage. This matters when you handle a specimen: a parting plane runs where the twin runs, so it is unpredictable in a way an octahedral fluorite cleavage is not.
- Hardness 5 to 6 rules out the soft red look-alikes. Earthy hematite feels soft because it is a powder of hard grains, not because the mineral is soft. A knife blade will not scratch a compact crystal face.
- Density 5.26 is the second check. That is twice quartz at 2.65 and noticeably heavier than magnetite is light. A hand-sized reniform mass is unmistakably heavy for its bulk, which is why kidney ore is recognised by weight long before it is tested.
- The classic British locality is Cleator Moor in Cumbria, which the Handbook names for the species. Elba and the St Gotthard area in Switzerland produced the crystallised material; Minas Gerais in Brazil and the Kuruman district in South Africa the large crystals.
| Mineral | Streak | Hardness | Density | What separates it |
|---|---|---|---|---|
| Hematite | Cherry-red to reddish brown | 5–6 | 5.26 | The streak. No cleavage, parting only |
| Magnetite | Black | 5.5–6.5 | 5.2 | Strongly magnetic; black streak |
| Goethite | Yellowish brown | 5–5.5 | 3.3–4.3 | Brown streak, and much lighter in the hand |
| Ilmenite | Black to brownish red | 5–6 | 4.7 | Weakly magnetic; streak rarely as red |
| Rutile | Pale brown | 6–6.5 | 4.2 | Adamantine lustre, prismatic with knee twins |
| Cassiterite | White to pale brown | 6–7 | 6.9 | Much denser; near-white streak from a dark mineral |
The streak test, done properly
A streak plate is a piece of unglazed porcelain with a hardness of about 6.5, and hematite at 5 to 6 will mark it. Drag the specimen firmly once, then look at the powder rather than at the scratch. Hematite leaves cherry-red to reddish-brown powder every time, whether the specimen is a black mirror-bright rosette from the Alps or a dull red lump from an iron formation.
This is the one test that does not care what the specimen looks like, and it is why hematite is the species most often identified correctly by beginners and most often mis-catalogued by everyone else. The colour of the mineral in hand is nearly useless: the Handbook of Mineralogy lists it as steel-grey, sometimes with an iridescent tarnish, and separately as dull to bright red, and in reflected light as white to grey-white with a bluish tint and deep blood-red internal reflections.
Where the test fails: on a specimen you are not willing to mark. A gemmy or mirror-faced crystal should never be streaked, because the mark is permanent. Use an inconspicuous edge, or use density and the absence of magnetism instead. If the specimen is small enough that any streak would be visible, it is a micromount and the question should be settled under the microscope. We cover the sequence in how to identify a mineral specimen.
Parting is not cleavage, and it changes how you handle the specimen
Hematite is one of the standard examples of a mineral with no cleavage at all. What collectors read as cleavage on a hematite plate is parting: the Handbook records it on {0001} and on {10-11}, and attributes it directly to twinning. Penetration twins occur on {0001} or with {10-10} as the composition plane, and lamellar twinning on {10-11} is common.
The practical difference is that cleavage is a property of the species and parting is a property of the individual specimen. Every fluorite anywhere will split on the octahedron. Only a twinned hematite parts, and it parts along whatever twin it happens to contain. You cannot predict from one specimen how the next one will behave, and a specimen that looks solid can separate along a plane you could not see.
For a micaceous or specular plate that means supporting the whole plate when lifting it rather than taking it by an edge. For a rosette — the “iron rose” habit, radiating platy crystals — it means never gripping the blades. Cleavage, parting and fracture sets out how to tell the three apart on an unknown specimen.
Kidney ore, specularite and iron roses: one species, four collections
Hematite covers an unusually wide range of habits for a single species, and the trade names attached to them are habit names rather than varieties in any mineralogical sense.
Kidney ore is the reniform to botryoidal habit, smooth and bulbous outside, radiating fibrous within. Cleator Moor in Cumbria is the locality the Handbook names in England, and West Cumberland kidney ore is the British collector's benchmark. Specularite is the micaceous to platy habit with a bright metallic lustre; it is the same species, and the sparkle is the {0001} plates. Iron roses are the rosette groupings of platy crystals, the Alpine habit from Fibbia and the St Gotthard in Uri and from Cavradi in Graubünden. Oolitic and earthy hematite is the sedimentary material, a common cement in red sandstones.
Crystals reach 13 cm, with triangular striations on {0001} and {10-11} — the striations are diagnostic when they are present, and they are what distinguishes a good Alpine plate from a good Brazilian one at a glance. The very large crystals come from Minas Gerais in Brazil, at Mesa Redonda and Congonhas do Campo.
If you are building a species suite rather than a locality suite, hematite is a species where four specimens are not redundant, because the four habits teach different things. Our species notes cover the rest of the iron and copper suite, and specific material we are looking for is listed on the wanted list.
Haematite or hematite, and does the spelling matter
Both spellings are correct and refer to the same species. Hematite is the spelling used by the IMA-CNMNC list of valid mineral species and by most modern literature; haematite is the traditional British form and is what you will read on older British labels and in nineteenth-century collections. The Handbook of Mineralogy gives the name as from the Greek for blood, in allusion to the colour — which is the streak, not the specimen.
Do not correct an old label. A label reading “Haematite, Cleator Moor” in a Victorian hand is a historical document, and rewriting the spelling destroys more than it tidies. Record the modern species name in your catalogue and leave the label alone. That is the same convention we set out in how to label and catalogue a collection.