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  2. Hematite - Wikipedia

    en.wikipedia.org/wiki/Hematite

    Hematite (/ ˈ h iː m ə ˌ t aɪ t, ˈ h ɛ m ə-/), also spelled as haematite, is a common iron oxide compound with the formula, Fe 2 O 3 and is widely found in rocks and soils. [6] Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of Fe 2 O 3. It has the same crystal structure as corundum ...

  3. Karelianite - Wikipedia

    en.wikipedia.org/wiki/Karelianite

    Formula (repeating unit) V 2 O 3: Identification; Color: Black: Luster: ... oxide, V 2 O 3. In terms of chemistry it is vanadium-analogue of hematite, corundum ...

  4. Psilomelane - Wikipedia

    en.wikipedia.org/wiki/Psilomelane

    Formula (repeating unit) General formula: Ba(Mn 2+)(Mn 4+) ... known as black hematite, despite not being related to true hematite, which is an iron oxide. Formula

  5. Corundum - Wikipedia

    en.wikipedia.org/wiki/Corundum

    Corundum is a crystalline form of aluminium oxide (Al 2 O 3) typically containing traces of iron, titanium, vanadium, and chromium. [3] [4] It is a rock-forming mineral.It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. [7]

  6. Maghemite - Wikipedia

    en.wikipedia.org/wiki/Maghemite

    Maghemite (Fe 2 O 3, γ-Fe 2 O 3) is a member of the family of iron oxides.It has the same formula as hematite, but the same spinel ferrite structure as magnetite (Fe 3 O 4) and is also ferrimagnetic.

  7. Dessauite- (Y) - Wikipedia

    en.wikipedia.org/wiki/Dessauite-(Y)

    Dessauite-(Y) is a mineral member of the crichtonite group with the formula (Sr,Pb)(Y,U)(Ti,Fe 3+) 20 O 38. It is associated with derbylite, hematite, rutile, karelianite, siderite, and calcite. Founded in the Buca della Vena Mine, Tuscany, Italy, the mineral was called dessauite in honor of professor Gabor Dessau (1907–1983). [2]

  8. Ferrihydrite - Wikipedia

    en.wikipedia.org/wiki/Ferrihydrite

    [12] [13] The six-line form has been classified as a mineral by the IMA in 1973 [14] with the nominal chemical formula 5 Fe 2 O 3 ·9 H 2 O. [15] Other proposed formulas are Fe 5 HO 8 ·4 H 2 O [16] and Fe 2 O 3 ·2 FeO(OH) ·2.6 H 2 O. [17] However, its formula is fundamentally indeterminate as its water content is variable.

  9. Ulvöspinel - Wikipedia

    en.wikipedia.org/wiki/Ulvöspinel

    Ulvöspinel or ulvite is an iron titanium oxide mineral with formula: Fe 2 Ti O 4 or TiFe 2+ 2 O 4. It forms brown to black metallic isometric crystals with a Mohs hardness of 5.5 to 6. It belongs to the spinel group of minerals, as does magnetite , Fe 3 O 4 .