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Lecontite
A valid IMA mineral species - grandfathered
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About Lecontite
John Lawrence LeConte
Formula:
(NH4)Na(SO4) · 2H2O
Colour:
Colourless; colourless in transmitted light
Lustre:
Vitreous
Hardness:
2 - 2½
Specific Gravity:
1.745
Crystal System:
Orthorhombic
Name:
Named in honor of John Lawrence LeConte (13 May 1825, New York City, New York, USA - 15 November 1883, Philadelphia, Pennsylvania, USA), an entomologist who provided the first specimens for study. He was responsible for naming and describing approximately half of the insect taxa known in the United States during his lifetime.
This page provides mineralogical data about Lecontite.
Unique Identifiers
Mindat ID:
2364
Long-form identifier:
mindat:1:1:2364:7
Similar Names
| Lefontite | A valid IMA mineral species - pending publication | Fe2Al2Be(PO4)2(OH)6 |
IMA Classification of Lecontite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
(N3-H4)Na(S6+O4)(H2O)2
First published:
1858
Type description reference:
Classification of Lecontite
7.CD.15
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
D : With only large cations
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
D : With only large cations
29.2.1.1
29 : HYDRATED ACID AND NORMAL SULFATES
2 : A2XO4·xH2O
29 : HYDRATED ACID AND NORMAL SULFATES
2 : A2XO4·xH2O
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 |
|---|---|---|
| Lcn | 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 Lecontite
Vitreous
Transparency:
Transparent
Colour:
Colourless; colourless in transmitted light
Streak:
White
Hardness:
2 - 2½ on Mohs scale
Density:
1.745 g/cm3 (Measured) 1.747 g/cm3 (Calculated)
Comment:
Synthetic
Optical Data of Lecontite
Type:
Biaxial (-)
RI values:
nα = 1.44 nβ = 1.454 nγ = 1.455
2V:
Measured: 40° to 43°, Calculated: 28°
Max. Birefringence:
δ = 0.015
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
Dispersion:
dispersion not observed
Optical Extinction:
X = c; Y = a; Z = b.
Chemistry of Lecontite
Mindat Formula:
(NH4)Na(SO4) · 2H2O
Element Weights:
Crystallography of Lecontite
Crystal System:
Orthorhombic
Class (H-M):
222 - Disphenoidal
Space Group:
P212121
Cell Parameters:
a = 8.216(8) Å, b = 12.854(1) Å, c = 6.232(8) Å
Ratio:
a:b:c = 0.639 : 1 : 0.485
Unit Cell V:
658.15 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Thin prismatic crystals; also very short and wide, very fine grained masses.
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| 0009882 | Lecontite | Arzt S, Glazer A M (1994) The optical activity and absolute optical chirality of NaNH4SO4*2H2O Acta Crystallographica B50 425-431 |  | 1994 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.038 Å | (100) |
| 5.085 Å | (83) |
| 4.649 Å | (83) |
| 4.972 Å | (67) |
| 3.783 Å | (56) |
| 3.325 Å | (56) |
| 3.923 Å | (50) |
Comments:
Las Piedras Cave, Honduras. Data from Faust and Bloss (1963).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 45a : [Sulfates, arsenates, selenates, antimonates] | |
| 45b : [Other oxidized fumarolic minerals] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 52 : Guano- and urine-derived minerals | <0.4 |
Geological Setting:
Early breakdown product of bat guanno
Type Occurrence of Lecontite
General Appearance of Type Material:
Crystals, some being an inch in length and narrow prisms, others short, not exceeding one-sixteenth of an inch and quite broad.
Place of Conservation of Type Material:
Yale University, New Haven, Connecticut, USA, 1696.
Geological Setting of Type Material:
Cave, in bat guano.
Other Language Names for Lecontite
Common Associates
Associations Based on Photo Data:
| 14 photos of Lecontite associated with Salammoniac | NH4Cl |
| 1 photo of Lecontite associated with Mascagnite | (NH4)2SO4 |
| 1 photo of Lecontite associated with Copiapite | Fe2+Fe3+4(SO4)6(OH)2 · 20H2O |
| 1 photo of Lecontite associated with Chalcanthite | CuSO4 · 5H2O |
| 1 photo of Lecontite associated with Thénardite | Na2SO4 |
Related Minerals - Strunz-mindat Grouping
| 7.CD. | Argesite | (NH4)7Bi3Cl16 |
| 7.CD. | Campostriniite | (Bi3+,Na)3(NH4,K)2Na2(SO4)6 · H2O |
| 7.CD.05 | Matteuccite | NaHSO4 · H2O |
| 7.CD.10 | Mirabilite | Na2SO4 · 10H2O |
| 7.CD.20 | Hydroglauberite | Na10Ca3(SO4)8 · 6H2O |
| 7.CD.25 | Eugsterite | Na4Ca(SO4)3 · 2H2O |
| 7.CD.30 | Görgeyite | K2Ca5(SO4)6 · H2O |
| 7.CD.35 | Syngenite | K2Ca(SO4)2 · H2O |
| 7.CD.35 | Antofagastaite | Na2Ca(SO4)2 · 1.5H2O |
| 7.CD.35 | Koktaite | (NH4)2Ca(SO4)2 · H2O |
| 7.CD.40 | Gypsum | CaSO4 · 2H2O |
| 7.CD.45 | Chinleite-(Y) | NaY(SO4)2 · H2O |
| 7.CD.45 | Bassanite | Ca(SO4) · 0.5H2O |
| 7.CD.45 | Chinleite-(Nd) | NaNd(SO4)2 · H2O |
| 7.CD.45 | Chinleite-(Ce) | NaCe(SO4)2(H2O) |
| 7.CD.50 |
F2 fumarole field, Mullet Island, Salton Sea, Imperial County, California, USA