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Formicaite
A valid IMA mineral species
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About Formicaite
Formula:
Ca(HCOO)2
Colour:
White with bluish tint
Lustre:
Vitreous
Hardness:
1
Specific Gravity:
1.9
Crystal System:
Tetragonal
Name:
For its chemical composition: the FORMate of CAlcium.
Dimorph of:
Naturally occurring calcium formate - one of just two such minerals currently known (compare dashkovaite).
Unique Identifiers
Mindat ID:
6954
Long-form identifier:
mindat:1:1:6954:6
IMA Classification of Formicaite
Approved
IMA Formula:
Ca(HCOO)1-2
Approval year:
1998
First published:
1999
Classification of Formicaite
10.AA.05
10 : ORGANIC COMPOUNDS
A : Salts of organic acids
A : Formates, Acetates, etc.
10 : ORGANIC COMPOUNDS
A : Salts of organic acids
A : Formates, Acetates, etc.
Dana 7th ed.:
50.2.3.1
Mineral Symbols
As of 2021 there are now IMAāCNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Fmc | IMAāCNMNC | Warr, L.N. (2021). IMAāCNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Formicaite
Vitreous
Transparency:
Translucent
Colour:
White with bluish tint
Streak:
White
Hardness:
1 on Mohs scale
Comment:
H=1 for compact aggregates
Tenacity:
Brittle
Cleavage:
Perfect
{001}
{001}
Density:
1.9(1) g/cm3 (Measured) 1.93(2) g/cm3 (Calculated)
Optical Data of Formicaite
Type:
Uniaxial (+)
RI values:
nω = 1.553 nε = 1.573
Max. Birefringence:
δ = 0.020
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 Āµm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 Āµm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Low (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Formicaite
Mindat Formula:
Ca(HCOO)2
Element Weights:
Elements listed:
Crystallography of Formicaite
Crystal System:
Tetragonal
Class (H-M):
422 - Trapezohedral
Space Group:
P41212
Cell Parameters:
a = 6.79(4) Å, c = 9.50 Å
Ratio:
a:c = 1 : 1.399
Unit Cell V:
437.99 Ć
Ā³ (Calculated from Unit Cell)
Z:
4
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.54 Ć | (90) |
| 3.40 Ć | (100) |
| 3.19 Ć | (60) |
| 2.859 Ć | (80) |
| 2.196 Ć | (70) |
| 1.947 Ć | (60) |
Comments:
Almost identical to that of synthetic Ca Ī²-formiate
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations |
Type Occurrence of Formicaite
General Appearance of Type Material:
Compact cryptocrystalline and colloform masses, and as aggregates in which the crystals are tabular and up to 5 Ć 30 Ć 30 Āµm. Also in a veinlet in skarnified marble.
Place of Conservation of Type Material:
A. E. Fersman Mineralogical Museum, Moscow, Russia.
Geological Setting of Type Material:
Hydrothermal veinlets that cut kurchatovite-sakhaite ore at the skarn deposit.
Associated Minerals at Type Locality:
Synonyms of Formicaite
Other Language Names for Formicaite
Related Minerals - Strunz-mindat Grouping
| 10.AA. | Henrysunite | Na2(C2H3O3)2(H2O) |
| 10.AA.10 | Dashkovaite | Mg(HCOO)2 Ā· 2H2O |
| 10.AA.20 | Acetamide | CH3CONH2 |
| 10.AA.25 | Calclacite | Ca(CH3COO)Cl Ā· 5H2O |
| 10.AA.30 | Paceite | CaCu(CH3COO)4 Ā· 6H2O |
| 10.AA.35 | Hoganite | Cu(CH3COO)2 Ā· H2O |
| 10.AA.40 | Lianbinite | (NH4)(C2H3O3)(C2H4O3) |
| 10.AA.40 | Domitrovicite | Zn(C2H3O3)2 Ā· 2H2O |
| 10.AA.40 | Puschridgeite | Mn(C2H3O3)2(H2O)2 |
| 10.AA.40 | Lazaraskeite | Cu(C2H3O3)2 |
| 10.AA.40 | Glecklerite | Na(C2H3O3) |
| 10.AA.40 | Jimkrieghite | Ca(C2H3O3)2 |
| 10.AA.40 | Stanevansite | Mg(C2H3O3)2 Ā· 2H2O |
| 10.AA.40 | Rasmussenite | Ca(C2H3O3)2 Ā· 3H2O |
| 10.AA.45 | Marchettiite | C5H7N5O3 |
Fluorescence of Formicaite
Some specimens have a weak, light bluish luminescence in shortwave ultraviolet light.
Other Information
IR Spectrum:
Absorption bands at 791, 1364, 1380, and 1603 (very strong), 2870 (weak), and 2925 cmā1 (very weak).
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 Formicaite
mindat.org URL:
https://www.mindat.org/min-6954.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Formicaite
Reference List:
Jambor, John L., Pertsev, Nikolai N., Roberts, Andrew C. (2000) New Mineral Names. American Mineralogist, 85. 1321-1325
Localities for Formicaite
Showing 4 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ā - 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.
Russia (TL) | |
| Chukanov et al. (1999) +1 other reference |
| maurice.strahlen.org (2004) |
| Chukanov et al. (1999) +1 other reference |
USA | |
| Gunnar FƤrber - Mineralienliste 1-2018 +2 other references |
Quick NavTopAbout FormicaiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesStrunz-MindatFluorescence Other InformationInternet Links References Localities Locality List
Solongo B deposit, Ozernoe ore cluster, Yeravninsky District, Buryatia, Russia