Charmarite-3T
A structural variant of Charmarite
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About Charmarite-3T
Charles and Marcelle Weber
Formula:
Mn2+4Al2(CO3)(OH)12 · 3H2O
Colour:
Orange-brown to pale brown
Lustre:
Vitreous
Hardness:
2
Specific Gravity:
2.48
Crystal System:
Trigonal
Name:
Named for Charles (1917-2003) and Marcelle (1918-2003) Weber, amateur mineralogists of Guilford, Connecticut, USA, who contributed extensively to the knowledge of Mt. St.-Hilaire and also found the first specimens of charmarite (the 2H polytype). Stephen and Janet Cares found the first specimens of the 3T polytype.
A polytype of Charmarite
The 3T polytype was originally described from Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry), Mont Saint-Hilaire, Rouville Co., Québec, Canada.
The 3T polytype was originally described from Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry), Mont Saint-Hilaire, Rouville Co., Québec, Canada.
Unique Identifiers
Mindat ID:
6863
Long-form identifier:
mindat:1:1:6863:1
Classification of Charmarite-3T
5.00.
5 : CARBONATES (NITRATES)
0 :
0 :
5 : CARBONATES (NITRATES)
0 :
0 :
Physical Properties of Charmarite-3T
Vitreous
Transparency:
Transparent
Colour:
Orange-brown to pale brown
Streak:
White
Hardness:
2 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
{001}
{001}
Fracture:
Irregular/Uneven
Density:
2.48(1) g/cm3 (Measured) 2.50 g/cm3 (Calculated)
Optical Data of Charmarite-3T
Type:
Uniaxial (-)
Comments:
ω = brown; ε = pale brown.
Comments:
Epsilon not measured.
Chemistry of Charmarite-3T
Mindat Formula:
Mn2+4Al2(CO3)(OH)12 · 3H2O
Element Weights:
Crystallography of Charmarite-3T
Crystal System:
Trigonal
Class (H-M):
32 - Trapezohedral
Cell Parameters:
a = 10.985(3) Å, c = 22.63(3) Å
Ratio:
a:c = 1 : 2.06
Unit Cell V:
2,364.91 ų (Calculated from Unit Cell)
Z:
6
Morphology:
Thin {0001} plates forming caps at the free end of prismatic crystals or as stacked tabular crystals that taper off at the other end to give an overall appearance of a nail. Common forms include {0001} and {1010}.
Twinning:
Twinning by rotation of 180° about c to give 3H pseudosymmetry.
Comment:
P3112 or P32l2
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.55 Å | (100) |
| 3.770 Å | (90) |
| 2.670 Å | (70) |
| 2.346 Å | (70) |
| 1.973 Å | (60) |
| 1.586 Å | (30) |
| 1.662 Å | (30) |
Comments:
Poudrette quarry, Mont Saint-Hilaire, Québec, Canada. The data are from the type description.
Synonyms of Charmarite-3T
Related Minerals - Strunz-mindat Grouping
| 5.00. | 'Charmarite-2H' | Mn2+4Al2(CO3)(OH)12 · 3H2O |
Fluorescence of Charmarite-3T
Not fluorescent.
Other Information
Notes:
Attacked by 1:1 HCl and HNO3 with effervescence, and dissolve in 1:1 H2SO4 with effervescence.
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 Charmarite-3T
mindat.org URL:
https://www.mindat.org/min-6863.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Charmarite-3T
Reference List:
Chao, G. Y., Gault, R. A. (1997) Quintinite-2H, quintinite-3T, charmarite-2H, charmarite-3T and caresite-3T, a new group of carbonate minerals related to the hydrotalcite-manasseite group. The Canadian Mineralogist, 35 (6) 1541-1549
Zhitova, Elena S., Zolotarev, Andrey A., Kasatkin, Anatoly V., Sheveleva, Rezeda M., Krivovichev, Sergey V., Pekov, Igor V., Bocharov, Vladimir N. (2024) The crystal structure of charmarite – the first case of a 11 × 11 Å superstructure mesh in layered double hydroxides. Mineralogical Magazine, 1-29 doi:10.1180/mgm.2024.11
Localities for Charmarite-3T
Showing 1 localities.
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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.
Canada | |
| Chao et al. (1997) |
Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada