Brassite Mineral Data

Brassite Mineral Data +

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General Brassite Information

Chemical Formula:

Mg(AsO3OH)·4(H2O)

Composition:

Molecular Weight = 236.29 gm

Magnesium 10.29 % Mg 17.06 % MgO

Arsenic 31.71 % As 48.63 % As₂O₅

Hydrogen 3.84 % H 34.31 % H₂O

Oxygen 54.17 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg(AsO₃OH)·4(H₂O)

Environment:

A rare reaction product of arsenic-rich solutions with Ca-Mg carbonates.

IMA Status:

Approved IMA 1973

Locality:

From Jachymov (Joachimsthal), Czech Republic. Link to MinDat.org Location Data.

Name Origin:

Honoring Rejane Brasse, who first synthesized the compound.

Synonym:

ICSD 78

PDF 23-1228

Brassite Image

Images:

Brassite

Comments: Opaque white botryoidal masses of brassite on matrix.
Location: Mine de Salsigne, Aude, France. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Brassite Crystallography

Axial Ratios:

a:b:c =0.686:1:1.5228

Cell Dimensions:

a = 7.472, b = 10.891, c = 16.585, Z = 8; V = 1,349.65 Den(Calc)= 2.33

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: P bca

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

By Intensity(I/I_o): 4.97(1), 3.2(0.8), 4.14(0.6),

Crystal Structure:

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drag2 - RMB Resize/Rotate
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Protas J , Gindt R , Acta Crystallographica, Section B , 32 (1976) p.1460-1466, Structure cristalline de la brassite, MgHAsO4*4H2O, produit de deshydratation, de la roesslerite, Locality: synthetic

Physical Properties of Brassite

Cleavage:

[001] Perfect

Color:

White.

Density:

2.28

Streak:

white

Optical Properties of Brassite

Gladstone-Dale:

CI meas= -0.044 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2345,KPDmeas= 0.2396,KC= 0.2296

Optical Data:

Biaxial (+), a=1.531, b=1.546, g=1.562, bire=0.0310

Calculated Properties of Brassite

Electron Density:

r_electron=2.33 gm/cc
note: r_Brassite=2.33 gm/cc.

Fermion Index

Fermion Index = 0.01055
Boson Index = 0.98945

Photoelectric:

PE_Brassite= 20.91 barns/electron
U=PE_Brassite x r_electron= 48.66 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Brassite is Not Radioactive

Brassite Classification

Dana Class:

39.1.7.1 (39)Hydrated Acid Phosphates, etc

(39.1)A+ [HXO4] · x(H2O)

(39.1.7)Dana Group

39.1.7.1 Brassite Mg(AsO3OH)·4(H2O) P bca 2/m 2/m 2/m

Strunz Class:

VII/C.15-10 VII - Phosphates, Arsenates and Vanadates

VII/C - Water-bearing phosphates without unfamiliar anions. cations of medium and small size: Be and Mn, Fe, Cu, Zn, Mg

VII/C.15 - Brassite - Rösslerite series

VII/C.15-10 Brassite Mg(AsO3OH)·4(H2O) P bca 2/m 2/m 2/m

VII/C.15-20 Phosphorrosslerite Mg(PO3OH)·7(H2O) A2/a 2/m

VII/C.15-30 Rosslerite Mg(AsO3OH)·7(H2O) A2/a 2/m

Other Brassite 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 Brassite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 - WWW-MINCRYST 13 -École des Mines de Paris

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Brassite

Mg(AsO3OH)·4(H2O)
Dana No: 39.1.7.1 Strunz No: VII/C.15-10
Locality:

Notes: