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Unnamed (Mcgovernite-like mineral)
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Formula:
(Mn,Mg,Fe3+)273As3+~12As5+~30Si~42O324(OH)252
Colour:
Light to bright yellow
Crystal System:
Hexagonal
A mineral similar to, but not necessarily identical to Mcgovernite. Lacks Zn and has Al substitution for Fe.
Moore & Araki (1978) have shown that mcgovernite is very closely related to hematolite and that mcgovernite has an 84-layer structure. Given that hematolite has 7 anions per layer, a more structurally sound basis for calculating a formula is 576 oxygens (588 less 12 for vacancies occupied by lone electron pairs of the As atoms in the (AsO3)3- groups) which yields the following full-cell formula for the Kombat material:
Mn198.82Mg66.85Fe3+ 0.98Al5.18As3+ 13.34 As5+ 31.01Si39.56.97O327.12(OH)248.88
versus the Sterling Hill formula:
Mn59.73Mg76.62Zn30.67Fe3+ 5.69As3+ 12.49As5+ 29.19Si41.11O322.97(OH)253.03 (Dunn et al 1988).
Moore & Araki (1978) have shown that mcgovernite is very closely related to hematolite and that mcgovernite has an 84-layer structure. Given that hematolite has 7 anions per layer, a more structurally sound basis for calculating a formula is 576 oxygens (588 less 12 for vacancies occupied by lone electron pairs of the As atoms in the (AsO3)3- groups) which yields the following full-cell formula for the Kombat material:
Mn198.82Mg66.85Fe3+ 0.98Al5.18As3+ 13.34 As5+ 31.01Si39.56.97O327.12(OH)248.88
versus the Sterling Hill formula:
Mn59.73Mg76.62Zn30.67Fe3+ 5.69As3+ 12.49As5+ 29.19Si41.11O322.97(OH)253.03 (Dunn et al 1988).
Unique Identifiers
Mindat ID:
29537
Long-form identifier:
mindat:1:1:29537:6
Physical Properties of Unnamed (Mcgovernite-like mineral)
Colour:
Light to bright yellow
Chemistry of Unnamed (Mcgovernite-like mineral)
Mindat Formula:
(Mn,Mg,Fe3+)273As3+~12As5+~30Si~42O324(OH)252
Element Weights:
Crystallography of Unnamed (Mcgovernite-like mineral)
Crystal System:
Hexagonal
Cell Parameters:
a = 8.224 Å, c = 204 Å
Ratio:
a:c = 1 : 24.805
Unit Cell V:
11,948.87 ų (Calculated from Unit Cell)
Other Information
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 Unnamed (Mcgovernite-like mineral)
mindat.org URL:
https://www.mindat.org/min-29537.html
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References for Unnamed (Mcgovernite-like mineral)
Localities for Unnamed (Mcgovernite-like mineral)
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The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
Namibia | |
| Dunn et al. (1988) |
