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Lacroixite

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Big Photo

Rusororo pegmatite, Gatumba District, Western Province, Rwanda
© 2008, JGW




Formula:
NaAl(PO
 
4
)F
System:MonoclinicColour:Colourless, light ...
Lustre:Sub-Vitreous, Resinous, DullHardness:4½
Member of:Tilasite Group
Name:
Named in 1914 by František Slavik in honor of Antoine François Alfred Lacroix [February 4, 1863 Macon, Saône-et-Loire, France - March 12, 1948 Paris, France], French mineralogist.
Dimorph of:Amblygonite Group


Frequently occurs a grains and rods in the altered margins of blocky crystals and grains of amblygonite or montebrasite embedded in granite pegmatite matrix. Not usually found in montebrasite crystals extending into cavities. Pure grains of lacroixite are uncommon.

Classification of Lacroixite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:7/B.25-40
Nickel-Strunz 10th (pending) edition ID:8.BH.10

8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
H : With medium-sized and large cations, (OH,etc.):RO4 = 1:1
Dana 8th edition ID:41.5.5.1

41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
5 : (AB)2(XO4)Zq
Hey's CIM Ref.:22.1.2

22 : Phosphates, Arsenates or Vanadates with other Anions
1 : Phosphates, arsenates or vanadates with fluoride
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Type Occurrence of Lacroixite

Type Locality:Greifenstein Rocks, Ehrenfriedersdorf, Erzgebirge, Saxony, Germany
General Appearance of Type Material:intergrowths, alteration rims, druses
Year of Discovery:1914
Geological Setting of type material:Granite pegmatites
Associated Minerals at type locality:
MuscoviteMoriniteMoriniteFluorapatiteFluorapatite
Elbaite

Physical Properties of Lacroixite

Lustre:Sub-Vitreous, Resinous, Dull
Diaphaneity (Transparency):Translucent
Colour:Colourless, light yellow, light green, almost white; colourless in transmitted light.
Streak:White
Hardness (Mohs):4½
Tenacity:Brittle
Cleavage:Poor/Indistinct
Parallel to (111) and 111) only.
Fracture:Irregular/Uneven
Density (measured):3.126 - 3.29 g/cm3
Density (calculated):3.29 g/cm3

Crystallography of Lacroixite

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:B2/b {B1 1 2/b} {C2/c} {C1 2/c 1}
Space Group Setting:C2/c
Cell Parameters:a = 6.414Å, b = 8.207Å, c = 6.885Å
β = 115.47°
Ratio:a:b:c = 0.782 : 1 : 0.839
Unit Cell Volume:V 327.20 ų (Calculated from Unit Cell)
Morphology:Usually massive or intergrown with other minerals. Rarely observed as fragmentary crystals.
Comment:Pseudo-orthorhombic
X-Ray Powder Diffraction:
d-spacingIntensity
4.73 (51)
4.627 (32)
3.155 (100)
2.895 (98)
2.476 (57)
2.166 (43)
1.578 (27)
Comments:ICDD 39-325

Optical Data of Lacroixite

Type:Biaxial (-)
RI values: nα = 1.546 nβ = 1.563 nγ = 1.580
2V:Measured: 89° , Calculated: 88°
Birefringence:0.034
Maximum Birefringence:δ = 0.034

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low
Dispersion:Slight r
Optical Extinction:Inclined

Chemical Properties of Lacroixite

Formula:
NaAl(PO
 
4
)F
Essential elements:Al, F, Na, O, P
All elements listed in formula:Al, F, Na, O, P

Relationship of Lacroixite to other Species

Member of:Tilasite Group
Other Members of Group:

- +
Durangite
NaAl(AsO
 
4
)F
Isokite
CaMg(PO
 
4
)F
Maxwellite
NaFe
3+
 
(AsO
 
4
)F
Panasqueiraite
CaMg(PO
 
4
)(OH,F)
Tilasite
CaMg(AsO
 
4
)F
Related Minerals - Nickel-Strunz Grouping):

- +
8.BH.05Thadeuite
Ca(Mg,Fe
2+
 
)
 
3
(PO
 
4
)
 
2
(OH,F)
 
2
8.BH.10Durangite
NaAl(AsO
 
4
)F
8.BH.10Isokite
CaMg(PO
 
4
)F
8.BH.10Maxwellite
NaFe
3+
 
(AsO
 
4
)F
8.BH.10Panasqueiraite
CaMg(PO
 
4
)(OH,F)
8.BH.10Tilasite
CaMg(AsO
 
4
)F
8.BH.15Drugmanite
Pb(Fe
3+
 
,Al)
 
2
(PO
 
4
)
 
2
(OH)
 
2
8.BH.20Bjarebyite
(Ba,Sr)(Mn
2+
 
,Fe
2+
 
,Mg)
 
2
Al
 
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.20Cirrolite
Ca
 
3
Al
 
2
(PO
 
4
)
 
3
(OH)
 
3
 (?)
8.BH.20Kulanite
Ba(Fe
2+
 
,Mn
2+
 
,Mg)
 
2
(Al,Fe
3+
 
)
 
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.20Penikisite
Ba(Mg,Fe
2+
 
,Ca)
 
2
Al
 
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.20Perloffite
Ba(Mn
2+
 
,Fe
2+
 
)
 
2
Fe
3+
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.20Johntomaite
BaFe
2+
2
Fe
3+
2
(PO
 
4
)
 
3
(OH)
 
3
8.BH.25Bertossaite
(Li,Na)
 
2
(Ca,Fe
2+
 
,Mn
2+
 
)Al
 
4
(PO
 
4
)
 
4
(OH,F)
 
4
8.BH.25Palermoite
(Li,Na)
 
2
(Sr,Ca)Al
 
4
(PO
 
4
)
 
4
(OH)
 
4
8.BH.30Carminite
PbFe
3+
2
(AsO
 
4
)
 
2
(OH)
 
2
8.BH.30Sewardite
CaFe
3+
2
(AsO
 
4
)
 
2
(OH)
 
2
8.BH.35Adelite
CaMg(AsO
 
4
)(OH)
8.BH.35Arsendescloizite
PbZn(AsO
 
4
)(OH)
8.BH.35Austinite
CaZn(AsO
 
4
)(OH)
8.BH.35Cobaltaustinite
CaCo(AsO
 
4
)(OH)
8.BH.35Conichalcite
CaCu(AsO
 
4
)(OH)
8.BH.35Duftite
PbCu(AsO
 
4
)(OH)
8.BH.35Gabrielsonite
PbFe(AsO
 
4
)(OH)
8.BH.35Nickelaustinite
Ca(Ni,Zn)(AsO
 
4
)(OH)
8.BH.35Tangeite
CaCu(VO
 
4
)(OH)
8.BH.35Gottlobite
CaMg(VO
 
4
,AsO
 
4
)(OH)
8.BH.35Hermannroseite
CaCu(PO
 
4
)(OH)
8.BH.40Čechite
Pb(Fe
2+
 
,Mn
2+
 
)(VO
 
4
)(OH)
8.BH.40Descloizite
Pb(Zn,Cu)(VO
 
4
)(OH)
8.BH.40Mottramite
PbCu(VO
 
4
)(OH)
8.BH.40Pyrobelonite
PbMn
2+
 
(VO
 
4
)(OH)
8.BH.45Bayldonite
PbCu
 
3
(AsO
 
4
)
 
2
(OH)
 
2
8.BH.45Vésigniéite
BaCu
 
3
(VO
 
4
)
 
2
(OH)
 
2
8.BH.50Paganoite
NiBi(AsO
 
4
)O
8.BH.55Jagowerite
BaAl
 
2
(PO
 
4
)
 
2
(OH)
 
2
8.BH.55Carlgieseckeite-(Nd)
NaNdCa
 
3
(PO
 
4
)
 
3
F
8.BH.60Attakolite
(Ca,Sr)Mn(Al,Fe)
 
4
(HPO
 
4
,PO
 
4
)
 
3
(SiO
 
4
,PO
 
4
)(OH)
 
4
8.BH.65Leningradite
PbCu
 
3
(VO
 
4
)
 
2
Cl
Related Minerals - Hey's Index Grouping:

- +
22.1.1Amblygonite
LiAl(PO
 
4
)F
22.1.3Natrophosphate
Na
 
7
(PO
 
4
)
 
2
F · 19H
 
2
O
22.1.5Nacaphite
Na
 
2
Ca(PO
 
4
)F
22.1.6Arctite
Na
 
2
Ca
 
4
(PO
 
4
)
 
3
F
22.1.7Nefedovite
Na
 
5
Ca
 
4
(PO
 
4
)
 
4
F
22.1.9Fluorapatite
Ca
 
5
(PO
 
4
)
 
3
F
22.1.10Herderite
CaBePO
 
4
(F,OH)
22.1.11Isokite
CaMg(PO
 
4
)F
22.1.12Panasqueiraite
CaMg(PO
 
4
)(OH,F)
22.1.13Babefphite
BaBePO
 
4
(F,OH)
22.1.14Fluellite
Al
 
2
(PO
 
4
)F
 
2
(OH) · 7H
 
2
O
22.1.15Minyulite
KAl
 
2
(PO
 
4
)
 
2
(OH,F) · 4H
 
2
O
22.1.16Morinite
NaCa
 
2
Al
 
2
(PO
 
4
)
 
2
(OH)F
 
4
 · 2H
 
2
O
22.1.17Bøggildite
Na
 
2
Sr
 
2
Al
 
2
PO
 
4
F
 
9
22.1.18Fluorstrophite
SrCaSr
 
3
(PO
 
4
)
 
3
F
22.1.19Viitaniemiite
Na(Ca,Mn
2+
 
)Al(PO
 
4
)(F,OH)
 
3
22.1.20Väyrynenite
Mn
2+
 
Be(PO
 
4
)(OH,F)
22.1.21Maxwellite
NaFe
3+
 
(AsO
 
4
)F
22.1.22Wagnerite
(Mg,Fe
2+
 
)
 
2
(PO
 
4
)F
22.1.23Triplite
(Mn
2+
 
,Fe
2+
 
)
 
2
(PO
 
4
)(F,OH)
22.1.24Magniotriplite
(Mg,Fe
2+
 
,Mn
2+
 
)
 
2
PO
 
4
F
22.1.25Zwieselite
(Fe
2+
 
,Mn
2+
 
)
 
2
(PO
 
4
)F
22.1.26Mcauslanite
HFe
2+
3
Al
 
2
(PO
 
4
)
 
4
F · 18H
 
2
O
22.1.27Richellite
CaFe
3+
2
(PO
 
4
)
 
2
(OH,F)
 
2
22.1.28Svabite
Ca
 
5
(AsO
 
4
)
 
3
F
22.1.29Tilasite
CaMg(AsO
 
4
)F
22.1.30Johnbaumite-M
Ca
 
5
(AsO
 
4
)
 
3
OH
22.1.31Durangite
NaAl(AsO
 
4
)F

Other Names for Lacroixite

Other Languages:
German:Lacroixit
Russian:Лакруаит
Spanish:Lacroixita

Other Information

Other Information:Readily soluble in HCl and H2SO4.
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 Lacroixite

Reference List:

- +
Slavík (1914) Bulletin de la Société française de Minéralogie: 37: 157.

Slavík (1914) Ac. sc. Bohéme Bulletin, no. 4: 19.

Slavík (1915) Ac. sc. Bohéme: 20: 372.

Larsen, E.S. and Berman, H. (1934) The Microscopic Determination of the Nonopaque Minerals, Second edition, USGS Bulletin 848: 159.

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, 1124 pp.: 783.

American Mineralogist (1972): 57: 1914.

Lahti, S.I. and Pajunen, A. (1985): New data on lacroixite, NaAlFPO4. American Mineralogist 70, 849-855.

Fransolet, A.M. (1989) The problem of Na-Li substitution in primary Li-Al phosphates; new data on lacroixite, a relatively widespread mineral. Canadian Mineralogist 27, 211-217.

Internet Links for Lacroixite

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    • Localities for Lacroixite

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    Hide Locality List
    (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.
    Australia
     
    • Victoria
      • East Gippsland Shire
        • Omeo
          • Mt Wills Mining District
            • Glen Wills
    		Eagle, R., Petrology, petrogenesis and mineralisation of granitic pegmatites of the Mount Wills district, northeastern Victoria
    Czech Republic
     
    • Bohemia (Böhmen; Boehmen)
      • Karlovy Vary Region
        • Aš (Asch)
    		Breiter K., Škoda R., Veselovský F.: Neobvyklý P-, Li- a Sn-bohatý pegmatit z Vernéřova u Aše, Česká republika. Bulletin Mineralogicko-petrografického oddělení Národního muzea v Praze, 2009, roč. 17, č. 1, s. 41-59.
        • Lázně Kynžvart (Bad Königswart)
    		Černý, P., Veselovský, F.: Pegmatit Bílý kámen (Weisser Stein) u Kynžvartu. Minerál, 2000, roč. 8, č. 1, s. 10-16.
    • Moravia (Mähren; Maehren)
      • Vysočina Region
        • Žďár nad Sázavou
    		Novák, M.: Amblygonit a produkty jeho přeměny v Li pegmatitu z Rožné. Minerál, 2001, roč. 9, č. 5, s. 326-327
    P. Pauliš (2001): Nejzajímavější naleziště Moravy a Slezska. Kuttna, Kutná Hora.
    Finland
     
    • Western and Inner Finland Region
      • Orivesi
        • Eräjärvi area
    		Sandström, F. & Lahti, S.I. (2009): Viitaniemipegmatiten i Eräjärvi, Orivesi, Finland. Litiofilen 26 (1): 11-38
    France
     
    • Auvergne
      • Allier
        • Ébreuil
          • Échassières
    		Econ Geol (1995) 90:548-576
    • Limousin
      • Creuse
        • Soumans
          • Montebras
    		Patureau, J., Chiappero, P-J. & Lebocey, J. (2011): Mines et minéraux de Montebras, Soumans, Creuse. Le Règne Minéral. 99, 5-33
    Germany
     
    • Saxony
      • Erzgebirge
        • Ehrenfriedersdorf
    		Bull. Int. Acad. Sci, Bohéme (1914): 4: 19; 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: 783; Wittern: "Mineralfundorte in Deutschland", 2001
    Rwanda
     
    • Western Province
      • Gatumba District
    		http://rruff.geo.arizona.edu/doclib/hom/lacroixite.pdf.; Daltry, V.D.C. and O. von Knorring (1998) Type-Mineralogy of Rwanda with Particular Reference to the Buranga Pegmatite. Geologica Belgica 1:1-9
    Fransolet, Andre-Mathieu, 1989, The Problem of Na-Li Substitution in Primary Li-Al Phosphates: New Data on Lacroixite, a Relatively Widespread Mineral, Canadian Mineralogist, v. 27, p. 211-217.
    European Journal of Mineralogy: 17(5): 749-759.
    Slovakia
     
    • Košice Region
      • Gelnica Co.
        • Henclová
    		Petrík, I., Kubiś, M., Konečný, P. & Malachovský, P. (2011): Rare phospates from the Surovec Topaz-Li-Mica microgranite, Gemeric Unit, Western Carpathians, Slovak Republik: Role of F/H2O of melt. Canadian Mineralogist. 49. 521-540
    USA
     
    • Connecticut
      • Middlesex Co.
        • Portland
          • Collins Hill
            • Strickland pegmatite (Strickland-Cramer Quarry; Strickland-Cramer Mine; Strickland-Cramer Feldspar-Mica Quarries)
    		Seaman, David (1976) Pegmatite Minerals of the World
    • Maine
      • Oxford Co.
        • Hebron
    		Fransolet, Andre-Mathieu, 1989, The Problem of Na-Li Substitution in Primary Li-Al Phosphates: New Data on Lacroixite, a Relatively Widespread Mineral, Canadian Mineralogist, v. 27, p. 211-217. Later http://rruff.geo.arizona.edu/doclib/hom/lacroixite.pdf.
    • Tennessee
      • Sevier Co.
        • East Fork District
          • East Fork Mine (East Fork manganese mine)
    		Travis A. Paris (2011) Tennessee mineral locality index. Rocks & Minerals, 86, #4, 300-328.
    Mineral and/or Locality
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    Copyright © Jolyon Ralph and Ida Chau 1993-2013. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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