Akrochordite Mineral Data

Akrochordite Mineral Data +

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General Akrochordite Information

Chemical Formula:

Mn4Mg(AsO4)2(OH)4·4(H2O)

Composition:

Molecular Weight = 661.99 gm

Magnesium 3.67 % Mg 6.09 % MgO

Manganese 33.20 % Mn 42.86 % MnO

Arsenic 22.64 % As 34.72 % As₂O₅

Hydrogen 1.83 % H 16.33 % H₂O

Oxygen 38.67 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₄Mg(AsO₄)₂(OH)₄·4(H₂O)

Environment:

A rare mineral in hausmannite ore from a metamorphosed Fe-Mn orebody (Långban, Sweden); in a metamorphosed stratiform zinc orebody (Sterling Hill, New Jersey, USA).

IMA Status:

Valid Species (Pre-IMA) 1922

Locality:

From Långban, Varmland, Sweden. At Sterling Hill, Ogdensburg, Sussex Co., New Jersey, USA. Link to MinDat.org Location Data.

Name Origin:

From the Greek for wart, for its typical habit.

Synonym:

ICSD 202938

PDF 20-715

Akrochordite Image

Images:

Click Here for Larger Akrochordite Image

Akrochordite Eveite

Comments: Micro crystals (to about 0.75mm) of very pale grayish green eveite in tiny vug with light pink akrochordite. Co-Type specimen & type locality.
Location: Langban, Varmland, Sweden. Scale: 13x10x4 mm.
© Tom Loomis / Dakota Matrix

Akrochordite Crystallography

Axial Ratios:

a:b:c =0.3223:1:0.3875

Cell Dimensions:

a = 5.682, b = 17.627, c = 6.832, Z = 2; beta = 99.49° V = 674.91 Den(Calc)= 3.26

Crystal System:

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

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

By Intensity(I/I_o): 4.4(1), 8.79(0.8), 2.75(0.5),

Crystal Structure:

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Moore P B , Sen Gupta P K , Schlemper E O , American Mineralogist , 74 (1989) p.256-262, Akrochordite, (Mn,Mg)5(OH)4(H2O)4(AsO4)2: A sheet structure with amphibole walls

Physical Properties of Akrochordite

Cleavage:

[???] Good

Color:

Reddish brown.

Density:

3.19 - 3.26, Average = 3.22

Diaphaniety:

Translucent

Hardness:

3.5 - Copper Penny

Optical Properties of Akrochordite

Gladstone-Dale:

CI meas= -0.007 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.003 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2077,KPDmeas= 0.2099,KC= 0.2084

Optical Data:

Biaxial (?), a=1.672, b=1.676, g=1.683, bire=0.0110

Calculated Properties of Akrochordite

Electron Density:

r_electron=3.13 gm/cc
note: r_Akrochordite=3.26 gm/cc.

Fermion Index

Fermion Index = 0.00385
Boson Index = 0.99615

Photoelectric:

PE_Akrochordite= 23.92 barns/electron
U=PE_Akrochordite x r_electron= 74.92 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Akrochordite is Not Radioactive

Akrochordite Classification

Dana Class:

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

(42.4)where (AB)5 (XO4)2 Zq · x(H2O)

(42.4.1)Dana Group

42.4.1.1 Akrochordite Mn4Mg(AsO4)2(OH)4·4(H2O) P 2₁/c 2/m

42.4.1.2 Guanacoite! Cu2Mg2(Mg,Cu)(OH)4(H2O)4(AsO4)2 P 2₁/c 2/m

Strunz Class:

VII/D.16-30 VII - Phosphates, Arsenates and Vanadates

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

VII/D.16 - Luetheite - Akrochordite series

VII/D.16-10 Luetheite Cu2Al2(AsO4)2(OH)4·(H2O) P 2₁/m 2/m

VII/D.16-20 Chenevixite Cu2Fe2(AsO4)2(OH)4·(H2O) P 2₁/m 2/m

VII/D.16-30 Akrochordite Mn4Mg(AsO4)2(OH)4·4(H2O) P 2₁/c 2/m

Other Akrochordite 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 Akrochordite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 - Franklin Minerals(Dunn) 5 -Google Images 6 -Google Scholar 7 -Handbook of Mineralogy (UofA) 8 -MinDAT 9 -MinMax(Deutsch) 10 -MinMax(English) 11 -Mineralienatlas (Deutsch) 12 -QUT Mineral Atlas 13 - WWW-MINCRYST 14 -École des Mines de Paris

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Akrochordite

Mn4Mg(AsO4)2(OH)4·4(H2O)
Dana No: 42.4.1.1 Strunz No: VII/D.16-30
Locality:

Notes: