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Chegemite

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Formula:
Ca7(SiO4)3(OH)2
Colour:
pink, yellow-pink to white.
Hardness:
5½ - 6
Specific Gravity:
2.86
Crystal System:
Orthorhombic
Name:
from the Chegem River where the new mineral was discovered in the headwater tributary-area
Ca- and OH-dominant analogue of Humite.
OH-analogue of Unnamed (F-analogue of Chegemite).


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Classification of ChegemiteHide

Approved
Approval Year:
2008

Physical Properties of ChegemiteHide

Colour:
pink, yellow-pink to white.
Streak:
white
Hardness:
5½ - 6 on Mohs scale
Hardness:
VHN100=315 - Vickers
Cleavage:
Imperfect/Fair
(010)
Fracture:
Conchoidal
Density:
2.86(1) g/cm3 (Measured)    2.892 g/cm3 (Calculated)

Optical Data of ChegemiteHide

Type:
Biaxial
RI values:
nα = 1.621(2) nβ = 1.626(3) nγ = 1.630(2)
Birefringence:
Max Birefringence:
δ = 0.009
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate

Chemical Properties of ChegemiteHide

Formula:
Ca7(SiO4)3(OH)2

Crystallography of ChegemiteHide

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 5.0696(1) Å, b = 11.3955(1) Å, c = 23.557(3) Å
Ratio:
a:b:c = 0.445 : 1 : 2.067
Unit Cell V:
1360.91 ų
Z:
4
Twinning:
Twins, probably on (110)
Comment:
space group Pbnm

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
5.611 (43)
3.646 (41)
3.041 (65)
2.837 (60)
2.728 (74)
2.557 (43)
2.520 (59)
1.910 (100)

Type Occurrence of ChegemiteHide

General Appearance of Type Material:
granular aggregates with grain sizes up to 5 mm
Place of Conservation of Type Material:
Fersman Mineralogical Museum in Moscow, Russia, with the number 3731/1 and the single grain used for structural investigation is deposited in the Museum of Natural History in Bern, Switzerland, with the number NMBE 39571.
Geological Setting of Type Material:
a rock-forming mineral in high-temperature skarns (sanadinite) in calcareous xenoliths in ignimbrites
Associated Minerals at Type Locality:

Synonyms of ChegemiteHide

Other Language Names for ChegemiteHide

Relationship of Chegemite to other SpeciesHide

Other Members of this group:
EdgrewiteCa9(SiO4)4F2 Mon. 2/m : P21/b
KumtyubeiteCa5(SiO4)2F2Mon. 2/m : P21/b
ReinhardbraunsiteCa5(SiO4)2(OH,F)2Mon. 2/m : P21/b
Forms a series with:

Common AssociatesHide

Associated Minerals Based on Photo Data:
Larnite3 photos of Chegemite associated with Larnite on mindat.org.
Hillebrandite2 photos of Chegemite associated with Hillebrandite on mindat.org.
Hydrogarnet1 photo of Chegemite associated with Hydrogarnet on mindat.org.
Rondorfite1 photo of Chegemite associated with Rondorfite on mindat.org.

Other InformationHide

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

References for ChegemiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Galuskin, E. V.; Gazeev, V. M.; Lazic, B.; Armbruster, T.; Galuskina, I. O.; Zadov, A. E.; Pertsev, N. N.; Wrzalik, R.; Dzierzanowski, P.; Gurbanov, A. G. & Bzowska, G. (2009): Chegemite Ca7(SiO4)3(OH)2 - a new humite-group calcium mineral from the Northern Caucasus, Kabardino-Balkaria, Russia. European Journal of Mineralogy 21, 1045-1059.

Internet Links for ChegemiteHide

Localities for ChegemiteHide

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

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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 (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Russia
 
  • Northern Caucasus Region
    • Kabardino-Balkarian Republic
      • Baksan Valley
Galuskin, E.V., Galuskina, I.O., Kusz, J., Gfeller, F., Armbruster, T., Bailau, R., Dulski, M., Gazeev, V.M., Pertsev, N.N., Zadov, A.E., Dzieržanowski, P. (2015): Mayenite supergroup, part II: Chlorkyuygenite from Upper Chegem, northern Caucasus Kabardino-Balkaria, Russia, a new microporous mayenite supergroup mineral with “zeolitic” H2O. European Journal of Mineralogy. 27, 113-122; Bailau, R., Gałuskin, E. V., Gazeev, V. M., & Gałuskina, I. O. Raman investigation of potential new mineral-Fe 3-analogue of wadalite from calcareous-silicate xenoliths of the Upper Chegem caldera, Northern Caucasus, Russia.
          • Lakargi Mt.
Galuskin, E. V.; Gazeev, V. M.; Lazic, B.; Armbruster, T.; Galuskina, I. O.; Zadov, A. E.; Pertsev, N. N.; Wrzalik, R.; Dzierzanowski, P.; Gurbanov, A. G. & Bzowska, G. (2009): Chegemite Ca7(SiO4)3(OH)2 - a new humite-group calcium mineral from the Northern Caucasus, Kabardino-Balkaria, Russia. European Journal of Mineralogy 21, 1045-1059.
Galuskin, E. V.; Gazeev, V. M.; Lazic, B.; Armbruster, T.; Galuskina, I. O.; Zadov, A. E.; Pertsev, N. N.; Wrzalik, R.; Dzierzanowski, P.; Gurbanov, A. G. & Bzowska, G. (2009): Chegemite Ca7(SiO4)3(OH)2 - a new humite-group calcium mineral from the Northern Caucasus, Kabardino-Balkaria, Russia. European Journal of Mineralogy 21, 1045-1059.
Mineral and/or Locality  
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