Legrandite Mineral Data

General Legrandite Information

Chemical Formula:

Zn2(AsO4)(OH)•(H2O)

Composition:

Molecular Weight = 304.72 gm

Zinc 42.92 % Zn 53.42 % ZnO

Arsenic 24.59 % As 37.71 % As₂O₅

Hydrogen 0.99 % H 8.87 % H₂O

Oxygen 31.50 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Zn₂(AsO₄)(OH)•(H₂O)

Environment:

Secondary mineral in zinc orebodies.

IMA Status:

Valid Species (Pre-IMA) 1932

Locality:

Ojuela mine near Mapimi, Durango. Link to MinDat.org Location Data.

Name Origin:

Named after the Belgian mining engineer, Legrande.

Name Pronunciation:

Legrandite + Pronunciation

Synonym:

ICSD 34846

PDF 42-11356

Legrandite Image

Images:

Legrandite

Comments: Prismatic crystal of yellow legrandite on a gossanous matrix.
Location: Mina Ojuela, Mapimi, Durango, Mexico. Scale: 2.5 x 1.7 x 1.4 cm.
© Fabre Minerals

Images:

Legrandite

Comments: Yellow crystals of legrandite partially covering an iron-oxide gossan.
Location: Oujela Mine, Mapimi, Durango, Mexico. Scale: Crystal size 6 mm.
© John Veevaert

Legrandite Crystallography

Axial Ratios:

a:b:c =1.612:1:1.2871

Cell Dimensions:

a = 12.8, b = 7.94, c = 10.22, Z = 8; beta = 104.2° V = 1,006.94 Den(Calc)= 4.02

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/c

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

By Intensity(I/I_o): 4.08(1), 5.93(0.71), 6.68(0.71),

Forms:

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Forms: ( 1 1 1) ( 1 0 0) ( 1 1 0) ( 0 0 1)

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Crystal Structure:

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McLean W J , Anthony J W , Finney J J , Laughon R B , American Mineralogist , 56 (1971) p.1147-1154, The crystal structure of legrandite

Physical Properties of Legrandite

Cleavage:

{100} Imperfect

Color:

Yellow, Yellowish orange.

Density:

Diaphaneity:

Translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

4-5 - Fluorite-Apatite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Legrandite

Gladstone-Dale:

CI meas= -0.008 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.003 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1762,KPDmeas= 0.1771,KC= 0.1756
Ncalc = 1.7 - 1.71

Optical Data:

Biaxial (+), a=1.675-1.702, b=1.69-1.709, g=1.735-1.74, bire=0.0380-0.0600, 2V(Calc)=52-62, 2V(Meas)=50.

Calculated Properties of Legrandite

Electron Density:

Bulk Density (Electron Density)=3.80 gm/cc
note: Specific Gravity of Legrandite =4.02 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Legrandite= 38.57 barns/electron
U=PE_Legrandite x rElectron Density= 146.55 barns/cc.

Radioactivity:

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

Legrandite Classification

Dana Class:

42.06.04.01 (42)Hydrated Phosphates, etc., Containing Hydroxyl or Halogen

(42.06)where (AB)2 (XO4) Zq · x(H2O)

(42.06.04)Strashimirite Group

42.06.04.01 Legrandite Zn2(AsO4)(OH)•(H2O) P 2₁/c 2/m

42.06.04.02 Spencerite Zn4(PO4)2(OH)2•3(H2O) P 2/c 2/m

Strunz Class:

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

08.D - Phosphates, etc

08.DC -With only medium-sized cations, (OH, etc.):RO4 = 1:1 and < 2:1

08.DC.10 Legrandite Zn2(AsO4)(OH)•(H2O) P 2₁/c 2/m

Other Legrandite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

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

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Ask about Legrandite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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

Legrandite

Zn2(AsO4)(OH)•(H2O)
Dana No: 42.06.04.01 Strunz No: 08.DC.10
Locality:

Notes: