Maghemite (original) (raw)

Formula:

(Fe3+0.67◻0.33)Fe3+2O4

Name:

From the first syllables of MAGnetite and HEMatite, in allusion to the magnetism and composition.

A ferromagnetic iron oxide (which may therefore be confused with magnetite).

Maghemite is formed by weathering or low-temperature oxidation of spinels containing ferrous iron, commonly magnetite or titanian magnetite. It is a widespread yellow pigment in continental sediments, rocks, and soils.

Long-form identifier:

mindat:1:1:2533:7

1e14c314-3fc5-4698-b6b5-42f6bb6fe75b

Approved, 'Grandfathered' (first described prior to 1959)

IMA status notes:

Redefined by the IMA

Approval history:

2018: Redefined as (Fe3+0.67◻0.33)Fe3+2O4, which better reflects its relation to the spinel supergroup. (Bosi et al., 2019).

4.BB.15

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
B : Metal: Oxygen = 3:4 and similar
B : With only medium-sized cations

4.3.7.1

4 : SIMPLE OXIDES
3 : A2X3

7.20.3

7 : Oxides and Hydroxides
20 : Oxides of Fe

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

Reflectivity:

Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 31.5%.

Colour in reflected light:

White to greyish blue

Mindat Formula:

(Fe3+0.67◻0.33)Fe3+2O4

Formerly given as Fe2O3.

Class (H-M):

432 - Gyroidal

Cell Parameters:

a = 8.3515 Å

Unit Cell V:

582.50 ų (Calculated from Unit Cell)

Morphology:

Commonly as coatings on or replacements of magnetite; massive; rarely as minute octahedral crystals, or acicular overgrowths.

Comment:

Cubic (P4132 or P4332), typically with a tetragonal supercell (P41 or P43, a = 8.35, c = 24.99 A).).

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Other Members of this group:

Associated Minerals Based on Photo Data:

Health Risks:

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.

• Ore
  • Iron ore
• Metamorphic rock
  • Impactite
    * Multiple impact impactite
    * Shock lithified impact regolith
    * Shock lithified impact regolith breccia
    * Regolith breccia
    * Martian basaltic breccia

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.