Ernstite Mineral Data

Ernstite Mineral Data +

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General Ernstite Information

Chemical Formula:

(Mn++1-xFe+++x)Al(PO4)(OH)2-xOx

Composition:

Molecular Weight = 210.86 gm

Manganese 13.03 % Mn 16.82 % MnO

Aluminum 12.80 % Al 24.18 % Al₂O₃

Iron 13.24 % Fe 18.93 % Fe₂O₃

Phosphorus 14.69 % P 33.66 % P₂O₅

Hydrogen 0.72 % H 6.41 % H₂O

Oxygen 45.53 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺_0.5Fe³⁺_0.5Al(PO₄)(OH)_1.5O_0.5

Environment:

Oxidation product of eosphoite in granitic pegmatite.

IMA Status:

Approved IMA 1970

Locality:

Daib-East farm, Karibib, Namibia. Link to MinDat.org Location Data.

Name Origin:

Named for Theodor K. A. Ernst (1904-), mineralogist, University of Erlangen, Germany.

Ernstite Image

Images:

Ernstite Schoonerite

Comments: 1 mm honey brown, acicular, radial sprays of ernstite with light green fibrous schoonerite and apatite in siderite.
Location: White Cap mine, Pennington County., South Dakota. Scale: Picture size 3 mm.
© Tom Loomis / Dakota Matrix

Ernstite Crystallography

Axial Ratios:

a:b:c =1.326:1:0.6639

Cell Dimensions:

a = 13.92, b = 10.497, c = 6.969, Z = 8; beta = 90.37° V = 1,018.28 Den(Calc)= 2.75

Crystal System:

MonoclinicSpace Group: C 2/c or Cc

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

By Intensity(I/I_o): 2.829(1), 2.836(0.8), 2.438(0.5),

Physical Properties of Ernstite

Cleavage:

[010] Good, [100] Good

Color:

Yellow brown.

Density:

3.07

Diaphaniety:

Translucent

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

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

Hardness:

3-3.5 - Calcite-Copper Penny

Optical Properties of Ernstite

Gladstone-Dale:

CI meas= -0.01 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.128 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2552,KPDmeas= 0.2286,KC= 0.2262

Optical Data:

Biaxial (-), a=1.678, b=1.706, g=1.721, bire=0.0430, 2V(Calc)=70, 2V(Meas)=74. Dispersion r > v.

Pleochroism (x):

yellow brown.

Pleochroism (y):

red brown.

Pleochroism (z):

pale yellow.

Calculated Properties of Ernstite

Electron Density:

r_electron=3.00 gm/cc
note: r_Ernstite=3.07 gm/cc.

Fermion Index

Fermion Index = 0.00302
Boson Index = 0.99698

Photoelectric:

PE_Ernstite= 8.34 barns/electron
U=PE_Ernstite x r_electron= 25.02 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Ernstite is Not Radioactive

Ernstite Classification

Dana Class:

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

(42.7)where (AB)5 (XO4)3 Zq · x(H2O)

(42.7.1)Dana Group

42.7.1.1 Childrenite FeAl(PO4)(OH)2·(H2O) Bba2 mm2

42.7.1.2 Eosphorite MnAl(PO4)(OH)2·(H2O) Bbam 2/m 2/m 2/m

42.7.1.3 Ernstite (Mn1-xFex)Al(PO4)(OH)2-xOx C 2/c or Cc Mono

42.7.1.4 Sinkankasite H2MnAl(PO4)2(OH)·6(H2O) P1 1

Strunz Class:

VII/D.14-30 VII - Phosphates, Arsenates and Vanadates

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

VII/D.14 - Childrenite - Ernstite series

VII/D.14-10 Childrenite FeAl(PO4)(OH)2·(H2O) Bba2 mm2

VII/D.14-20 Eosphorite MnAl(PO4)(OH)2·(H2O) Bbam 2/m 2/m 2/m

VII/D.14-30 Ernstite (Mn1-xFex)Al(PO4)(OH)2-xOx C 2/c or Cc Mono

Other Ernstite Information

References:

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

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Ernstite

(Mn++1-xFe+++x)Al(PO4)(OH)2-xOx
Dana No: 42.7.1.3 Strunz No: VII/D.14-30
Locality:

Notes: