Bulachite Mineral Data

Bulachite Mineral Data +

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General Bulachite Information

Chemical Formula:

Al2(AsO4)(OH)3·3(H2O)

Composition:

Molecular Weight = 297.95 gm

Aluminum 18.11 % Al 34.22 % Al₂O₃

Arsenic 25.15 % As 38.57 % As₂O₅

Hydrogen 3.04 % H 27.21 % H₂O

Oxygen 53.70 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Al₂(AsO₄)(OH)₃·3(H₂O)

IMA Status:

Approved IMA 1985

Locality:

Neubulach, northern Black Forest, Germany. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

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Bulachite Crystallography

Axial Ratios:

a:b:c =0.8734:1:0.3953

Cell Dimensions:

a = 15.53, b = 17.78, c = 7.03, Z = 10; V = 1,941.15 Den(Calc)= 2.55

Crystal System:

OrthorhombicSpace Group: Pmnm,P 2₁221,Pma2,P mn2₁

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

By Intensity(I/I_o): 7.78(1), 3.49(0.8), 8.97(0.7),

Physical Properties of Bulachite

Cleavage:

None

Color:

Colorless, White, Light green.

Density:

2.6

Diaphaniety:

Translucent

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

2 - Gypsum

Luster:

Silky

Streak:

white

Optical Properties of Bulachite

Gladstone-Dale:

CI meas= 0.072 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= 0.054 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2136,KPDmeas= 0.2095,KC= 0.2258

Optical Data:

Biaxial (-), a=1.54, b=1.546, g=1.548, bire=0.0080, 2V(Calc)=58, 2V(Meas)=66. Dispersion r > v.

Calculated Properties of Bulachite

Electron Density:

r_electron=2.53 gm/cc
note: r_Bulachite=2.55 gm/cc.

Fermion Index

Fermion Index = 0.00026
Boson Index = 0.99974

Photoelectric:

PE_Bulachite= 17.02 barns/electron
U=PE_Bulachite x r_electron= 43.10 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Bulachite is Not Radioactive

Bulachite Classification

Dana Class:

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

(42.6)where (AB)2 (XO4) Zq · x(H2O)

(42.6.7)Dana Group

42.6.7.1 Senegalite Al2(PO4)(OH)3·(H2O) P na2₁ mm2

42.6.7.2 Bulachite Al2(AsO4)(OH)3·3(H2O) Pmnm,P 2₁221,Pma2,P mn2₁ Ortho

Strunz Class:

VII/D.18-20 VII - Phosphates, Arsenates and Vanadates

VII/D - Water-bearing phosphates with unfamiliar anions, cations of medium size: Cu, Zn, Mn, Al, Fe

VII/D.18 - Senegalite - Fluellite series

VII/D.18-10 Senegalite Al2(PO4)(OH)3·(H2O) P na2₁ mm2

VII/D.18-20 Bulachite Al2(AsO4)(OH)3·3(H2O) Pmnm,P 2₁221,Pma2,P mn2₁ Ortho

VII/D.18-30 Fluellite Al2(PO4)F2(OH)·7(H2O) F ddd 2/m 2/m 2/m

Other Bulachite Information

References:

NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Bulachite :
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 -École des Mines de Paris

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

Bulachite

Al2(AsO4)(OH)3·3(H2O)
Dana No: 42.6.7.2 Strunz No: VII/D.18-20
Locality:

Notes: