Irhtemite Mineral Data

Irhtemite Mineral Data +

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General Irhtemite Information

Chemical Formula:

Ca4Mg(AsO3OH)2(AsO4)2·4(H2O)

Composition:

Molecular Weight = 814.37 gm

Calcium 19.69 % Ca 27.54 % CaO

Magnesium 2.98 % Mg 4.95 % MgO

Arsenic 36.80 % As 56.45 % As₂O₅

Hydrogen 1.24 % H 11.06 % H₂O

Oxygen 39.29 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₄Mg(AsO₃OH)₂(AsO₄)₂·4(H₂O)

Environment:

Probably formed from the dehydration of picopharmacolite.

IMA Status:

Approved IMA 1972

Locality:

Irhtem ore deposit, Morocco. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Irhtemite Image

Images:

Irhtemite

Comments: Pink acicular divergent microcrystals of irhtemite on matrix.
Location: Irhtem Mine, near Bou-Azzer, Ouarzazate, Morocco. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Irhtemite Crystallography

Axial Ratios:

a:b:c =1.7647:1:1.1434

Cell Dimensions:

a = 16.73, b = 9.48, c = 10.84, Z = 4; beta = 97.25° V = 1,705.48 Den(Calc)= 3.17

Crystal System:

MonoclinicSpace Group: Unk

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

By Intensity(I/I_o): 2.963(1), 3.242(1), 2.847(0.9),

Physical Properties of Irhtemite

Color:

Colorless, White, Pale rose, Pink.

Density:

3.09

Diaphaniety:

Transparent to Translucent

Habit:

Spherical - Spherical, rounded aggregates.

Luster:

Silky

Streak:

white

Optical Properties of Irhtemite

Gladstone-Dale:

CI meas= -0.049 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.023 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2013,KPDmeas= 0.2065,KC= 0.1968

Optical Data:

Biaxial (+), a=1.634, g=1.642, bire=0.0080

Calculated Properties of Irhtemite

Electron Density:

r_electron=3.07 gm/cc
note: r_Irhtemite=3.17 gm/cc.

Fermion Index

Fermion Index = 0.00344
Boson Index = 0.99656

Photoelectric:

PE_Irhtemite= 27.22 barns/electron
U=PE_Irhtemite x r_electron= 83.49 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Irhtemite is Not Radioactive

Irhtemite Classification

Dana Class:

39.2.5.1 (39)Hydrated Acid Phosphates, etc

(39.2)H2 (AB)5 (XO4)4 · x(H2O)

(39.2.5)Dana Group

39.2.5.1 Irhtemite Ca4Mg(AsO3OH)2(AsO4)2·4(H2O) Unk Mono

Strunz Class:

VII/C.24-30 VII - Phosphates, Arsenates and Vanadates

VII/C - Water-bearing phosphates without unfamiliar anions, cations of medium and big size: Fe, Mn, Zn, Mg and Ca, (NH4)1+

VII/C.24 - Haidingerite - Picropharmacolite series

VII/C.24-10 Haidingerite Ca(AsO3OH)·(H2O) Pcnb 2/m 2/m 2/m

VII/C.24-20 Mcnearite NaCa5H4(AsO4)5·4(H2O) P1,P 1 Tri

VII/C.24-30 Irhtemite Ca4Mg(AsO3OH)2(AsO4)2·4(H2O) Unk Mono

VII/C.24-40 Vladimirite Ca5(AsO3OH)2(AsO4)2·5(H2O) P 2₁/c 2/m

VII/C.24-50 Ferrarisite Ca5(AsO3OH)2(AsO4)2·9(H2O) P1 1

VII/C.24-60 Guerinite Ca5(AsO3OH)2(AsO4)2·9(H2O) P 2₁/n 2/m

VII/C.24-70 Rauenthalite Ca3(AsO4)2·10(H2O) P1 1

VII/C.24-80 Phaunouxite Ca3(AsO4)·11(H2O) P1 1

VII/C.24-90 Picropharmacolite Ca4Mg(AsO3OH)2(AsO4)2·11(H2O) P1 1

Other Irhtemite Information

References:

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

See Also:

Links to other databases for Irhtemite :
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 Irhtemite Specimen Label here :

Irhtemite

Ca4Mg(AsO3OH)2(AsO4)2·4(H2O)
Dana No: 39.2.5.1 Strunz No: VII/C.24-30
Locality:

Notes: