Lansfordite
A valid IMA mineral species - grandfathered
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About Lansfordite
Lansford, Pennsylvania, USA
Formula:
MgCO3 · 5H2O
Colour:
Colourless (fresh), white (exposed); colourless in transmitted light.
Lustre:
Vitreous
Hardness:
2½
Specific Gravity:
1.6
Crystal System:
Monoclinic
Name:
After the town of Lansford, Pennsylvania, USA, near where it was initially found.
Stable for several months at room temperature(Nestola et al., 2017), but may slowly dehydrate, ultimately altering to nesquehonite.
Unique Identifiers
Mindat ID:
2324
Long-form identifier:
mindat:1:1:2324:1
IMA Classification of Lansfordite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
MgCO3(H2O)5
First published:
1888
Classification of Lansfordite
5.CA.10
5 : CARBONATES (NITRATES)
C : Carbonates without additional anions, with H2O
A : With medium-sized cations
5 : CARBONATES (NITRATES)
C : Carbonates without additional anions, with H2O
A : With medium-sized cations
15.1.6.1
15 : HYDRATED NORMAL CARBONATES
1 : A(XO3)·xH2O
15 : HYDRATED NORMAL CARBONATES
1 : A(XO3)·xH2O
11.3.4
11 : Carbonates
3 : Carbonates of Mg
11 : Carbonates
3 : Carbonates of Mg
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Lfd | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Lansfordite
Vitreous
Transparency:
Translucent
Colour:
Colourless (fresh), white (exposed); colourless in transmitted light.
Streak:
White
Hardness:
2½ on Mohs scale
Hardness Data:
Measured
Cleavage:
Perfect
On {001}, on {100} less perfect.
On {001}, on {100} less perfect.
Density:
1.6 g/cm3 (Measured) 1.7 g/cm3 (Calculated)
Optical Data of Lansfordite
Type:
Biaxial (+)
RI values:
nα = 1.465 nβ = 1.468 nγ = 1.507
Max. Birefringence:
δ = 0.042
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 µm 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 µm 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:
Moderate (negative)
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (32°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (32°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
r > v strong
Optical Extinction:
X = b; Z = c; Y ⊥ {100}.
Chemistry of Lansfordite
Mindat Formula:
MgCO3 · 5H2O
Element Weights:
Elements listed:
Crystallography of Lansfordite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/c
Setting:
P21/c
Cell Parameters:
a = 7.3458 Å, b = 7.6232 Å, c = 12.4737 Å
β = 101.722°
β = 101.722°
Ratio:
a:b:c = 0.964 : 1 : 1.636
Unit Cell V:
683.81 ų
Z:
4
Morphology:
Minute short-prismatic crystals [001]; also stalactitic.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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CIF File Best | x | y | z | a | b | c
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0015442 | Lansfordite | Liu B N, Zhou X T, Cui X S, Tang J G (1990) Synthesis of lansfordite MgCO3*5H2O and its crystal structure investigation Science in China B33 1350-1356 | 1990 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.839 Å | (100) |
| 4.583 Å | (95) |
| 3.237 Å | (55) |
| 1.710 Å | (33) |
| 5.239 Å | (31) |
| 5.110 Å | (31) |
| 7.178 Å | (30) |
Comments:
Synthetic
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 49 : Oxic cellular biomineralization (see also #44) | <0.54 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| 53 : Other minerals with taphonomic origins | <0.4 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals |
Type Occurrence of Lansfordite
General Appearance of Type Material:
Small stalactites attached to carbonaceous shale.
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, USA (type).
Geological Setting of Type Material:
Anthracite coal mine underground workings.
Associated Minerals at Type Locality:
Other Language Names for Lansfordite
Common Associates
Associations Based on Photo Data:
| 5 photos of Lansfordite associated with Nesquehonite | MgCO3 · 3H2O |
| 3 photos of Lansfordite associated with 'Barringtonite' | MgCO3 · 2H2O |
| 2 photos of Lansfordite associated with Magnesite | MgCO3 |
Related Minerals - Strunz-mindat Grouping
| 5.CA.05 | Nesquehonite | MgCO3 · 3H2O |
| 5.CA.15 | 'Barringtonite' | MgCO3 · 2H2O |
| 5.CA.20 | Hellyerite | NiCO3 · 5.5H2O |
Other Information
Notes:
Effloresces readily, altering to nesquehonite. Soluble in dilute acids with effervescence.
Special Storage/
Display Requirements:
Display Requirements:
Slowly effloresces at room temperature, altering to nesquehonite.
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 Lansfordite
mindat.org URL:
https://www.mindat.org/min-2324.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Lansfordite
Reference List:
Poitevin, Eugene (1924) A new occurrence of lansfordite from Atlin, B. C. American Mineralogist, 9 (11) 225-227
Hill, R. J., Canterford, J. H., Moyle, F. J. (1982) New data for lansfordite. Mineralogical Magazine, 46 (341) 453-457 doi:10.1180/minmag.1982.046.341.08
Garvie, Laurence A.J. (2003) Decay-induced biomineralization of the saguaro cactus (Carnegiea gigantea) American Mineralogist, 88 (11) 1879-1888 doi:10.2138/am-2003-11-1231
Localities for Lansfordite
Showing 26 localities.
symbol to view information about a locality.
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.
Austria | |
| Offenbacher (1983) |
| Meixner (1950) | |
| J.Taucher (2001) | |
| Exel (1993) |
| |
Canada | |
| Poitevin (1924) +1 other reference |
| Tomes et al. (2013) +1 other reference |
| Wilson (2006) | |
Germany | |
| Knoll (2004) |
| Gerhard Möhn collection | |
Greece | |
| Kolitsch et al. (2014) |
Italy | |
| Fenoglio (1933) +2 other references |
| Piccoli et al. (2007) |
Norway | |
| Lu et al. (2023) |
| Taagvold (2015) |
| Hamza Sito Collection |
| Moore et al. (1980) |
Pacific Ocean | |
| Pisciotto et al. (1992) |
Poland | |
| Warchulski et al. (2014) |
Slovakia | |
| Majzlan et al. (2016) |
Switzerland | |
| Lapis 32 (11) +2 other references |
USA | |
| Garvie (2003) |
| Garvie (2003) +1 other reference | |
| Eckel et al. (1997) |
| Palache et al. (1951) |
| S. Gordon pg. 68. +3 other references |
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Sommergraben, Sankt Stefan ob Leoben, Leoben District, Styria, Austria