Hongheite (original) (raw)

A valid IMA mineral species

Formula:

Ca19Fe2+Al4(Fe3+,Mg)8(◻4)B[Si2O7]4[(SiO4)10]O(OH,O)9

The formula is a partial simplification of the full structural formula. The large (VII-IX)-coordinated (X4)2(X3)8(X2)8(X1) sites are here combined (e.g. Ca19) and are typically filled with Ca, although other large cations such as the REE may be present. The square-pyramidal Y1 site can host a variety of M2+ and M3+ ions and is the basis for the distinction of several species. The VI-coordinated Y2 site typically is filled with Al, whereas the also VI-coordinated Y3 site may contain Al, Mg, and other cations of similar charge and size. The tetrahedral T1 site is typically vacant but may contain B (less commonly Al); the trigonal T2 site is also typically vacant but may also contain B. Some of the (SiO4) may be replaced by (H4O4), akin to the Si4+ ↔︎ 4H+ hydrogarnet substitution. Among the oxygen that are not part of the silica tetrahedra, there are eight "O11" that typically occur as OH, two "O10" that are typically O & OH or OH & OH (the latter arrangement notably when Y1 is an M2+ cation). There may also be up to three "O12" that in most vesuvianite-group minerals are absent (and are not included here), but may be present particularly when T1 is occupied.

Note that because the Y3 site occupancy of "end-member" hongheite has not been explicitly defined, and that based on other vesuvianite-group minerals it could be likely considered as either (Fe3+4Mg4) or (Fe3+6Mg2) (with charge-balancing concomitant occupancy of the "O11" position as [OH]9 or [(OH)7O2], respectively), the more generic occupancies denoted by (Fe3+,Mg)8 and (OH,O)9 have been maintained here, pending further data.

Crystal System:

Tetragonal

First Fe(II)- and Fe(III)-dominant member of the group. B occupies the trigonal T2 site, and excess B may partially occupy the tetrahedral T1 site. Also somewhat chemically related to another member - milanriederite.

Unique IdentifiersHide

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Long-form identifier:

mindat:1:1:52166:0

9011316d-3b61-4201-b431-7adfc8c884e6

IMA Classification of HongheiteHide

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IMA Formula:

Ca19Fe2+Al4(Fe3+,Mg,Al)8(◻,B)4BSi18O69(O,OH)9

Classification of HongheiteHide

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9.BG.35

9 : SILICATES (Germanates)
B : Sorosilicates
G : Sorosilicates with mixed SiO4 and Si2O7 groups; cations in octahedral [6] and greater coordination

Mineral SymbolsHide

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

Physical Properties of HongheiteHide

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Streak:

Pale greyish green

Fracture:

Irregular/Uneven

Density:

3.446 g/cm3 (Measured) 3.423 g/cm3 (Calculated)

Optical Data of HongheiteHide

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RI values:

_n_ω = 1.720(2) _n_ε = 1.725(2)

δ = 0.005

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Chemistry of HongheiteHide

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Mindat Formula:

Ca19Fe2+Al4(Fe3+,Mg)8(◻4)B[Si2O7]4[(SiO4)10]O(OH,O)9

The formula is a partial simplification of the full structural formula. The large (VII-IX)-coordinated (X4)2(X3)8(X2)8(X1) sites are here combined (e.g. Ca19) and are typically filled with Ca, although other large cations such as the REE may be present. The square-pyramidal Y1 site can host a variety of M2+ and M3+ ions and is the basis for the distinction of several species. The VI-coordinated Y2 site typically is filled with Al, whereas the also VI-coordinated Y3 site may contain Al, Mg, and other cations of similar charge and size. The tetrahedral T1 site is typically vacant but may contain B (less commonly Al); the trigonal T2 site is also typically vacant but may also contain B. Some of the (SiO4) may be replaced by (H4O4), akin to the Si4+ ↔︎ 4H+ hydrogarnet substitution. Among the oxygen that are not part of the silica tetrahedra, there are eight "O11" that typically occur as OH, two "O10" that are typically O & OH or OH & OH (the latter arrangement notably when Y1 is an M2+ cation). There may also be up to three "O12" that in most vesuvianite-group minerals are absent (and are not included here), but may be present particularly when T1 is occupied.

Note that because the Y3 site occupancy of "end-member" hongheite has not been explicitly defined, and that based on other vesuvianite-group minerals it could be likely considered as either (Fe3+4Mg4) or (Fe3+6Mg2) (with charge-balancing concomitant occupancy of the "O11" position as [OH]9 or [(OH)7O2], respectively), the more generic occupancies denoted by (Fe3+,Mg)8 and (OH,O)9 have been maintained here, pending further data.

Crystallography of HongheiteHide

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Crystal System:

Tetragonal

Class (H-M):

4/m m m _(_4/_m_2/_m_2/m ) - Ditetragonal Dipyramidal

Cell Parameters:

a = 15.667(3) Å, c = 11.725(1) Å

Unit Cell V:

2,877.96 ų (Calculated from Unit Cell)

Morphology:

Radiating acicular to prismatic. Dominant crystal forms are {100}, {110}, {101} and {001}.

X-Ray Powder DiffractionHide

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Powder Diffraction Data:

Geological EnvironmentHide

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Type Occurrence of HongheiteHide

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General Appearance of Type Material:

Radiating acicular to prismatic aggregates 4 to 25 mm in diameter. Also in vugs as well- formed, euhedral and prismatic crystals 0. 5-4. 0 mm long and 0. 3-1. 0 mm thick.

Place of Conservation of Type Material:

Mineralogical collections of the Geological Museum of China, Beijing, China, catalogue number M13579.

Geological Setting of Type Material:

In endoskarn of granite that is adjacent to a skarn Sn deposit.

Associated Minerals at Type Locality:

Relationship of Hongheite to other SpeciesHide

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Other Members of this group:

Related Minerals - Strunz-mindat GroupingHide

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Other InformationHide

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Health Risks:

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

Internet Links for HongheiteHide

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References for HongheiteHide

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Reference List:

Xu Jinsha, Li Guowu, Fan Guang, Ge Xiangkun, Zhu Xiangping, Shen Ganfu. (2019) Ca18(□,Ca)2Fe2+Al4(Fe3+,Mg,Al)8(□,B)4BSi18O69(O,OH)9 — a new mineral from the Fushanite Group. Acta Geological Sinica, 1.

Localities for HongheiteHide

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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.

Locality ListHide

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- 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.