Brassite Mineral Data

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.

Name Pronunciation:

Brassite

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 - Dipyramidal H-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),

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
Ncalc = 1.52 - 1.53

Optical Data:

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

Calculated Properties of Brassite

Electron Density:

Bulk Density (Electron Density)=2.33 gm/cc
note: Specific Gravity of Brassite =2.33 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Brassite= 20.91 barns/electron
U=PE_Brassite x rElectron Density= 48.66 barns/cc.

Radioactivity:

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

Brassite Classification

Dana Class:

39.01.07.01 (39)Hydrated Acid Phosphates, etc

(39.01)A+ [HXO4] ï¿½ x(H2O)

(39.01.07)Dana Group

39.01.07.01 Brassite Mg(AsO3OH)•4(H2O) P bca 2/m 2/m 2/m

Strunz Class:

08.CE.15 08 - PHOSPHATES, ARSENATES, VANADATES

08.C - Phosphates without Additional Anions, with H2O

08.CE -With only medium-sized cations, RO4:H2O ï¿½ 1:2.5

08.CE.15 Brassite Mg(AsO3OH)•4(H2O) P bca 2/m 2/m 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 - 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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Brassite

Mg(AsO3OH)•4(H2O)
Dana No: 39.01.07.01 Strunz No: 08.CE.15
Locality:

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