Ahlfeldite Mineral Data

Ahlfeldite Mineral Data +

General Ahlfeldite Information

Chemical Formula:

(Ni,Co)SeO3·2(H2O)

Composition:

Molecular Weight = 221.74 gm

Cobalt 6.64 % Co 8.45 % CoO

Nickel 19.85 % Ni 25.26 % NiO

Hydrogen 1.82 % H 16.25 % H₂O

Selenium 35.61 % Se 50.04 % SeO₂

Oxygen 36.08 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ni_0.75Co_0.25(SeO₃)·2(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1935

Locality:

Bolivia, Potosí, Colquechaca Link to MinDat.org Location Data.

Synonym:

ICSD 69220

PDF 25-1233

Ahlfeldite Image

Images:

Ahlfeldite

Comments: Green encrustations of ahlfeldite on matrix.
Location: Mina El Dragon, Potosi, Bolivia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Ahlfeldite Crystallography

Axial Ratios:

a:b:c =0.8595:1:0.734

Cell Dimensions:

a = 7.53, b = 8.76, c = 6.43, Z = 4; beta = 99.083° V = 418.82 Den(Calc)= 3.52

Crystal System:

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

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

By Intensity(I/I_o): 5.69(1), 3.426(0.8), 2.992(0.75),

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Crystal Structure:

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Wildner M , Neues Jahrbuch fur Mineralogie, Monatshefte , 1990 (1990) p.353-362, Crystal structure refinements of synthetic cobaltomenite (CoSeO3*2H2O), and ahlfeldite (NiSeO3*2H2O)

Physical Properties of Ahlfeldite

Cleavage:

[110] Distinct, [103] Distinct

Color:

Pink brown, Apple green, Red.

Density:

3.37

Diaphaniety:

Transparent

Hardness:

2-2.5 - Gypsum-Finger Nail

Luster:

Vitreous (Glassy)

Streak:

light green

Optical Properties of Ahlfeldite

Gladstone-Dale:

CI meas= -0.047 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.002 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2129,KPDmeas= 0.2224,KC= 0.2124

Optical Data:

Biaxial (-), a=1.709, b=1.752, g=1.787, bire=0.0780, 2V(Calc)=82, 2V(Meas)=85.

Calculated Properties of Ahlfeldite

Electron Density:

r_electron=3.36 gm/cc
note: r_Ahlfeldite=3.52 gm/cc.

Fermion Index

Fermion Index = 0.02948
Boson Index = 0.97052

Photoelectric:

PE_Ahlfeldite= 36.69 barns/electron
U=PE_Ahlfeldite x r_electron= 123.20 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Ahlfeldite is Not Radioactive

Ahlfeldite Classification

Dana Class:

34.2.3.3 (34)Selenites - Tellurites - Sulfites

(34.2)as A++ XO3 · x(H2O)

(34.2.3)Dana Group

34.2.3.1 Clinochalcomenite CuSeO3·2(H2O) P 2₁/n 2/m

34.2.3.2 Cobaltomenite CoSeO3·2(H2O) P 2₁/n 2/m

34.2.3.3 Ahlfeldite (Ni,Co)SeO3·2(H2O) P 2₁/m 2/m

Strunz Class:

IV/K.07-30 IV - Oxides

IV/K - Sulfides, selenides, tellurides with [XO3]2- groups and related structures

IV/K.07 - Clinochalcomenite - Ahlfeldite

IV/K.07-10 Clinochalcomenite CuSeO3·2(H2O) P 2₁/n 2/m

IV/K.07-20 Cobaltomenite CoSeO3·2(H2O) P 2₁/n 2/m

IV/K.07-30 Ahlfeldite (Ni,Co)SeO3·2(H2O) P 2₁/m 2/m

Other Ahlfeldite Information

References:

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

See Also:

Links to other databases for Ahlfeldite :
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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Ahlfeldite

(Ni,Co)SeO3·2(H2O)
Dana No: 34.2.3.3 Strunz No: IV/K.07-30
Locality:

Notes: