Lacroixite Mineral Data

General Lacroixite Information

Chemical Formula:

NaAl(PO4)F

Composition:

Molecular Weight = 163.94 gm

Sodium 14.02 % Na 18.90 % Na₂O

Aluminum 16.46 % Al 31.10 % Al₂O₃

Phosphorus 18.89 % P 43.29 % P₂O₅

Oxygen 39.04 % O

Fluorine 11.59 % F 11.59 % F

- % F -4.88 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

NaAl(PO₄)F

Environment:

In druses in granite.

IMA Status:

Valid Species (Pre-IMA) 1914

Locality:

Large crystals [from the Koppar quarry,] on the Greifensteine, near Ehrenfriedersdorf, Saxony, Germany. Link to MinDat.org Location Data.

Name Origin:

Named for Francois Antoine Alfred Lacroix (1863-1948), French mineralogist, Natural History Museum, Paris, France.

Name Pronunciation:

Lacroixite + Pronunciation

Synonym:

ICSD 40522

PDF 39-325

Lacroixite Image

Images:

Lacroixite Berlinite

Comments: Pale olive green crystalline lacroixite with white crystalline berlinite.
Location: Rusororo Pegmatite, Gatumba, Gisenyi, Rwanda. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Lacroixite Crystallography

Axial Ratios:

a:b:c =0.7815:1:0.8389

Cell Dimensions:

a = 6.414, b = 8.207, c = 6.885, Z = 4; beta = 115.47° V = 327.20 Den(Calc)= 3.33

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/c

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.9(1), 2.47(0.85), 3.159(0.71),

Physical Properties of Lacroixite

Cleavage:

{111} Indistinct, {111} Indistinct

Color:

Colorless, Gray, Gray white, Light green, Light yellow.

Density:

3.29

Hardness:

4.5 - Between Fluorite and Apatite

Luster:

Vitreous - Resinous

Streak:

white

Optical Properties of Lacroixite

Gladstone-Dale:

CI meas= 0.075 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= 0.086 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1691,KPDmeas= 0.1711,KC= 0.185
Ncalc = 1.61 - 1.62

Optical Data:

Biaxial (-), a=1.546, b=1.563, g=1.58, bire=0.0340, 2V(Calc)=88, 2V(Meas)=89.

Calculated Properties of Lacroixite

Electron Density:

Bulk Density (Electron Density)=3.21 gm/cc
note: Specific Gravity of Lacroixite =3.29 gm/cc.

Fermion Index:

Fermion Index = 0.0001873774
Boson Index = 0.9998126226

Photoelectric:

PE_Lacroixite= 1.67 barns/electron
U=PE_Lacroixite x rElectron Density= 5.35 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Lacroixite is Not Radioactive

Lacroixite Classification

Dana Class:

41.05.05.01 (41)Anhydrous Phosphates, etc. Containing Hydroxyl or Halogen

(41.05)where (A B)2 (XO4) Zq

(41.05.05)Lacroixite Group

41.05.05.01 Lacroixite NaAl(PO4)F C 2/c 2/m

41.05.05.02 Durangite NaAl(AsO4)F C 2/c 2/m

41.05.05.03 Maxwellite NaFe(AsO4)F Aa,A2/a Mono

Strunz Class:

08.BH.10 08 - PHOSPHATES, ARSENATES, VANADATES

08.B - Phosphates, etc. with Additional Anions, without H2O

08.BH -With medium-sized and large cations, (OH,etc.):RO4 = 1:1

08.BH.10 Durangite NaAl(AsO4)F C 2/c 2/m

08.BH.10 Isokite CaMg(PO4)F C 2/c 2/m

08.BH.10 Lacroixite NaAl(PO4)F C 2/c 2/m

08.BH.10 Maxwellite NaFe(AsO4)F Aa,A2/a Mono

08.BH.10 Panasqueiraite CaMg(PO4)(OH,F) C 2/c 2/m

08.BH.10 Tilasite CaMg(AsO4)F C 2/c 2/m

Other Lacroixite Information

References:

NAME( AntBidBlaNic4) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Lacroixite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Print or Cut-and-Paste your Lacroixite Specimen Label here :

Lacroixite

NaAl(PO4)F
Dana No: 41.05.05.01 Strunz No: 08.BH.10
Locality:

Notes:

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