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)

Environment:

Formed as an alteration product of penroseeite and other selenides.

IMA Status:

Valid Species (Pre-IMA) 1935

Locality:

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

Name Origin:

Named for Federico Ahlfeld (1892-192), German-Bolivian geologist and mineralogist who studied Bolivian minerals.

Name Pronunciation:

Ahlfeldite + Pronunciation

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),

Forms:

Mouse
Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize
Keyboard
S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu
Help on Above

Forms: ( 0 2 1) ( 1 1 0) ( 1 0 3) ( 1 0 1) ( 0 1 1)

Warning: this large pop-up is very compute intensive and may not work well with some computers.

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

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

Diaphaneity:

Transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

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

Hardness:

2-2.5 - Gypsum-Finger Nail

Luster:

Vitreous (Glassy)

Streak:

light green

Optical Properties of Ahlfeldite

Gladstone-Dale:

CI meas= -0.04 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.004 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2115,KPDmeas= 0.2209,KC= 0.2124
Ncalc = 1.72 - 1.75

Optical Data:

Biaxial (-), a=1.703, b=1.744, g=1.786, bire=0.0830, 2V(Calc)=88, 2V(Meas)=85. Dispersion r < v.

Pleochroism (x):

very pale green.

Pleochroism (y):

pale green.

Pleochroism (z):

green.

Calculated Properties of Ahlfeldite

Electron Density:

Bulk Density (Electron Density)=3.36 gm/cc
note: Specific Gravity of Ahlfeldite =3.52 gm/cc.

Fermion Index:

Fermion Index = 0.02
Boson Index = 0.98

Photoelectric:

PE_Ahlfeldite= 36.69 barns/electron
U=PE_Ahlfeldite x rElectron Density= 123.20 barns/cc.

Radioactivity:

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

Ahlfeldite Classification

Dana Class:

34.02.03.03 (34)Selenites - Tellurites - Sulfites

(34.02)as A++ XO3 · x(H2O)

(34.02.03)Chalcomenite Group (Monoclinic)

34.02.03.01 Clinochalcomenite CuSeO3•2(H2O) P 2₁/n 2/m

34.02.03.02 Cobaltomenite CoSeO3•2(H2O) P 2₁/n 2/m

34.02.03.03 Ahlfeldite (Ni,Co)SeO3•2(H2O) P 2₁/m 2/m

Strunz Class:

04.JH.10 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.J - Arsenites, Antimonites, Bismuthites, Sulfites,

04.JH -Selenites without additional anions, with H2O

04.JH.10 Ahlfeldite (Ni,Co)SeO3•2(H2O) P 2₁/m 2/m

04.JH.10 Clinochalcomenite CuSeO3•2(H2O) P 2₁/n 2/m

04.JH.10 Cobaltomenite CoSeO3•2(H2O) P 2₁/n 2/m

Other Ahlfeldite Information

References:

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

See Also:

Links to other databases for Ahlfeldite :
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

Search for Ahlfeldite using:

[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Ahlfeldite :

A Bijoux Google Search for Ahlfeldite
Adam's Minerals Google Search for Ahlfeldite
Cape Minerals Google Search for Ahlfeldite
Dakota Matrix Minerals Google Search for Ahlfeldite
Excalibur Mineral Corp. Google Search for Ahlfeldite
Exceptional Minerals Google Search for Ahlfeldite
John Betts Fine Minerals Search for Ahlfeldite
McDougall Minerals Google Search for Ahlfeldite
Mineral News Website Link
Rock and Mineral Shows Google Search for Ahlfeldite
Weinrich Minerals, Inc. Google Search for Ahlfeldite

Ask about Ahlfeldite 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 Ahlfeldite Specimen Label here :

Ahlfeldite

(Ni,Co)SeO3•2(H2O)
Dana No: 34.02.03.03 Strunz No: 04.JH.10
Locality:

Notes: