Chegemite Subgroup (original) (raw)
A group of related mineral species
About Chegemite SubgroupHide
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Formula:
Ca2nSinO4n · Ca(OH,F)2, n = 2,3,4
The chegemite subgroup constitutes a series of minerals with the general formula Ca2nSinO4n•Ca(OH,F)2 for n = 2,3,4, where n designates the number of olivine layers between each norbergite M(OH,F)2 layer in the structure. Both (OH)- and F-dominant species have been identified for some values of n.
The valid species of the humite polysomatic series, is according to IMA sept. 2021 (CNMNC Newsletter 63):
| The chegemite subgroup |
|---|
| n speciesformulan = 1 n = 2 Kumtyubeite Ca5(SiO4)2F2n = 2 Reinhardbraunsite Ca5(SiO4)2(OH)2n = 3 Fluorchegemite Ca7(SiO4)3F2n = 3 Chegemite Ca7(SiO4)3(OH)2n = 4 Edgrewite Ca9(SiO4)4F2n = 4 Hydroxyledgrewite Ca9(SiO4)4(OH)2 |
Note: There is currently no official IMA nomenclature for the humite group.
Unique IdentifiersHide
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Long-form identifier:
mindat:1:1:46188:1
5f146230-4de7-40d7-95ba-dce6349ad5ea
Chemistry of Chegemite SubgroupHide
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Mindat Formula:
Ca2nSinO4n · Ca(OH,F)2, n = 2,3,4
Crystal StructureHide
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| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0015581 | Reinhardbraunsite | Kuznetsova T P, Nevskii N N, Ilyukhin V V, Belov N V (1980) Refinement of the crystal structure of calcium chondrodite Ca5[SiO4]2(OH)2=Ca(OH)2*2Ca2SiO4 Soviet Physics Crystallography 25 91-92 | 1980 | synthetic | 0 | 293 | |
| 0015696 | Reinhardbraunsite | Kirfel A, Hamm H M, Will G (1983) The crystal structure of reinhardbraunsite, Ca5(SiO4)2(OH,F)2, a new mineral of the calcio-chondrodite type Tschermaks Mineralogische und Petrographische Mitteilungen 31 137-150 | 1983 | synthetic | 0 | 293 |
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Geological EnvironmentHide
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Geological Setting:
High temperatures/ low pressure environment, and then only in the contact between carbonate xenoliths and magma.
Synonyms of Chegemite SubgroupHide
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Relationship of Chegemite Subgroup to other SpeciesHide
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Other Members of this group:
Structurally related to group(s):
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 Chegemite SubgroupHide
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References for Chegemite SubgroupHide
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Localities for Chegemite SubgroupHide
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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.