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Lecontite

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Formula:
(NH
 
4
,K)NaSO
 
4
 · 2H
 
2
O
System:OrthorhombicColour:Colourless; colourless ...
Hardness:2 - 2½
Name:
After John L. LeConte (1825-1883), American entomologist, discoverer of the species.
This page provides mineralogical data about Lecontite.

Classification of Lecontite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:6/C.21-20
Nickel-Strunz 10th (pending) edition ID:7.CD.15

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
C : Sulfates (selenates, etc.) without additional anions, with H2O
D : With only large cations
Dana 8th edition ID:29.2.1.1

29 : HYDRATED ACID AND NORMAL SULFATES
2 : A2XO4·xH2O
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Type Occurrence of Lecontite

Type Locality:Las Piedras Cave, Comayagua Department, Honduras
Place of Conservation of Type Material:Yale University
Year of Discovery:1858
Geological Setting of type material:Cave

Occurrences of Lecontite

Geological Setting:Early breakdown product of bat guanno

Physical Properties of Lecontite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:Colourless; colourless in transmitted light
Hardness (Mohs):2 - 2½
Density (measured):1.745 g/cm3
Density (calculated):1.747 g/cm3
Comment:Synthetic

Crystallography of Lecontite

Crystal System:Orthorhombic
Class (H-M):2 2 2 - Disphenoidal
Space Group:P21 21 21
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 Volume:V 658.15 ų (Calculated from Unit Cell)
Z:4
Morphology:Thin prismatic crystals; also very short and wide, very fine grained masses.

Optical Data of Lecontite

Type:Biaxial (-)
RI values: nα = 1.440 nβ = 1.454 nγ = 1.455
2V:Measured: 40° to 43°, Calculated: 28°
Maximum Birefringence:δ = 0.015

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:dispersion not observed

Chemical Properties of Lecontite

Formula:
(NH
 
4
,K)NaSO
 
4
 · 2H
 
2
O
Essential elements:H, N, Na, O, S
All elements listed in formula:H, K, N, Na, O, S
Analytical Data:Soluble in water.
Relationship of Lecontite to other Species
Common Associates:
ThenarditeMascagnite
Related Minerals - Nickel-Strunz Grouping):

- + 
7.CD.05Matteuccite
NaHSO
 
4
 · H
 
2
O
7.CD.10Mirabilite
Na
 
2
SO
 
4
 · 10H
 
2
O
7.CD.20Hydroglauberite
Na
 
10
Ca
 
3
(SO
 
4
)
 
8
 · 6H
 
2
O
7.CD.25Eugsterite
Na
 
4
Ca(SO
 
4
)
 
3
 · 2H
 
2
O
7.CD.30Görgeyite
K
 
2
Ca
 
5
(SO
 
4
)
 
6
 · H
 
2
O
7.CD.35Koktaite
(NH
 
4
)
 
2
Ca(SO
 
4
)
 
2
 · H
 
2
O
7.CD.35Syngenite
K
 
2
Ca(SO
 
4
)
 
2
 · H
 
2
O
7.CD.40Gypsum
CaSO
 
4
 · 2H
 
2
O
7.CD.45Bassanite
CaSO
 
4
 · 0.5H
 
2
O
7.CD.50Zircosulfate
(Zr,Ti)(SO
 
4
)
 
2
 · 4H
 
2
O
7.CD.55Schieffelinite
Pb
 
8
(TeO
 
4
)
 
5
(SO
 
4
)
 
3
 · 8H
 
2
O
7.CD.60Montanite
Bi
 
2
(TeO
 
6
) · 2H
 
2
O
7.CD.65Omongwaite
Na
 
2
Ca
 
5
(SO
 
4
)
 
6
 · 3H
 
2
O
Other Names for Lecontite
Other Languages:
German:Lecontit
Russian:Леконтит
Spanish:Lecontita
Other Information
Other Information:Taste bitter, salty
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
References for Lecontite
Reference List:

- + 
Taylor (1858) American Journal of Science: 26: 273.



Dawson (1918) Journal of the Chemical Society of London: 113: 675.



Larsen, E.S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 99.



Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 438-439.



American Mineralogist (1963): 48: 180.



Acta Crystallographica (1967): 22: 683-687.


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    • Localities for Lecontite
    






    


    

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    (TL) indicates type locality.  ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.

    France
     
    

    • Nord-Pas-de-Calais
    

      • Pas-de-Calais
    
    		Naze-Nancy Masalehdani, M., Mees, F., Dubois, M., Coquinot, Y., Potdevin, J.-L., Fialin, M. & Blanc-Valleron, M.-M. (2009): Condensate minerals from a burning coal-waste heap in Avion, Northern France. Can. Mineral. 47, 573-591.
    Honduras
     
    

    • Comayagua Department
    
    		Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 439; American Mineralogist (1963): 48: 180; J.W. Anthony, R.A. Bideaux, K.W. Bladh, M.C. Nichols: Handbook of Mineralogy, Vol. V (2003)
    USA
     
    

    • Nevada
    

      • Washoe Co.
    
    		NBMG Spec. Pub. 31 Minerals of Nevada
    

    


    

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