Strengite Mineral Data

Strengite Mineral Data +

General Strengite Information

Chemical Formula:

Fe+++PO4·2(H2O)

Composition:

Molecular Weight = 186.85 gm

Iron 29.89 % Fe 42.73 % Fe₂O₃

Phosphorus 16.58 % P 37.98 % P₂O₅

Hydrogen 2.16 % H 19.28 % H₂O

Oxygen 51.38 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe³⁺(PO₄)·2(H₂O)

Environment:

Alteration of iron-bearing phosphates. Forms a series with variscite.

IMA Status:

Valid Species (Pre-IMA) 1877

Locality:

Eleonore iron mine, Giessen, near Waldgirmes, Thuringia, Germany Link to MinDat.org Location Data.

Name Origin:

Named after Johann August Streng (1830-1897), German mineralogist, University of Giessen, Germany.

Synonym:

Barrandite

Globosite

Strengite Image

Images:

Strengite

Comments: Pink, bladed, stellate spray of strengite crystals on matrix.
Location: Indian Mountain, Cherokee County, Alabama, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Strengite Cacoxenite

Comments: Lilac colored, spear-head shape crystals of strengite to 5mm in large, open vug associated with golden fibrous cacoxenite.
Location: Coon Creek, Polk Co., Arkansas, USA. Scale: Picture size 2 cm.
© Tom Loomis / Dakota Matrix

Images:

Strengite Kidwellite

Comments: Spherical, crystalline aggregate of purple strengite on green kidwellite.
Location: Three Oak Gap, Polk Co., Arkansas, USA. Scale: Crystal size 2 mm.
© Tom Loomis / Dakota Matrix

Strengite Crystallography

Axial Ratios:

a:b:c =1.0238:1:0.8823

Cell Dimensions:

a = 10.122, b = 9.886, c = 8.7233, Z = 8; V = 872.91 Den(Calc)= 2.84

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pcab

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

By Intensity(I/I_o): 3.114(1), 4.383(0.85), 5.509(0.6),

Crystal Structure:

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Taxer K , Bartl H , Crystal Research and Technology , 39 (2004) p.1080-1088, On the dimorphy between the variscite and clinovariscite group: refined, finestructural relationship of strengite and clinostrengite, Fe(PO4)*2H2O, Locality: Kreuzberg, Pleystein, Barvaria, Note: x(O3) corrected to match reported bond lengths

View Additional jPOWD Structure files for Strengite
[1]

Physical Properties of Strengite

Cleavage:

[010] Good, [001] Poor

Color:

Colorless, Pale violet, Deep violet, Red, Carmine red.

Density:

2.87

Diaphaniety:

Transparent to Translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Botryoidal - "Grape-like" rounded forms (e.g.. malachite).

Habit:

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

Habit:

Spherical - Spherical, rounded aggregates.

Hardness:

3.5 - Copper Penny

Luminescence:

None.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Strengite

Gladstone-Dale:

CI meas= 0.048 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.038 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2594,KPDmeas= 0.2567,KC= 0.2697

Optical Data:

Biaxial (+/-), a=1.71-1.74, b=1.72-1.75, g=1.74-1.76, bire=0.0200-0.0300, 2V(Calc)=72-88, 2V(Meas)=0-90. Dispersion relatively strong.

Pleochroism (x):

none.

Pleochroism (y):

none.

Pleochroism (z):

none.

Calculated Properties of Strengite

Electron Density:

r_electron=2.83 gm/cc
note: r_Strengite=2.84 gm/cc.

Fermion Index

Fermion Index = 0.00658
Boson Index = 0.99342

Photoelectric:

PE_Strengite= 9.60 barns/electron
U=PE_Strengite x r_electron= 27.13 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Strengite is Not Radioactive

Strengite Classification

Dana Class:

40.4.1.2 (40)Hydrated Phosphates, etc

(40.4)where A+++ XO4 · x(H2O)

(40.4.1)Dana Group

40.4.1.1 Variscite AlPO4·2(H2O) Pcab 2/m 2/m 2/m

40.4.1.2 Strengite FePO4·2(H2O) Pcab 2/m 2/m 2/m

40.4.1.3 Scorodite FeAsO4·2(H2O) Pcab 2/m 2/m 2/m

40.4.1.4 Mansfieldite AlAsO4·2(H2O) Pcab 2/m 2/m 2/m

40.4.1.5 Yanomamite In(AsO4)·2(H2O) P bca 2/m 2/m 2/m

Strunz Class:

VII/C.09-60 VII - Phosphates, Arsenates and Vanadates

VII/C - Water-bearing phosphates without unfamiliar anions. cations of medium and small size: Be and Mn, Fe, Cu, Zn, Mg

VII/C.09 - Variscite group

VII/C.09-10 Metavariscite AlPO4·2(H2O) P 2₁/n 2/m

VII/C.09-20 Phosphosiderite FePO4·2(H2O) P 2₁/n 2/m

VII/C.09-30 Kolbeckite ScPO4·2(H2O) P 2₁2₁2₁ 2 2 2

VII/C.09-35 Malhmoodite FeZr(PO4)2·4(H2O) P 2₁/c 2/m

VII/C.09-50 Variscite AlPO4·2(H2O) Pcab 2/m 2/m 2/m

VII/C.09-60 Strengite FePO4·2(H2O) Pcab 2/m 2/m 2/m

VII/C.09-70 Mansfieldite AlAsO4·2(H2O) Pcab 2/m 2/m 2/m

VII/C.09-80 Scorodite FeAsO4·2(H2O) Pcab 2/m 2/m 2/m

VII/C.09-85 Yanomamite In(AsO4)·2(H2O) P bca 2/m 2/m 2/m

VII/C.09-88 Parascorodite! FeAsO4·2(H2O) HEX ? Hex

VII/C.09-90 Koninckite FePO4·3(H2O)(?) Unk Tetra

Other Strengite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

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Strengite

Fe+++PO4·2(H2O)
Dana No: 40.4.1.2 Strunz No: VII/C.09-60
Locality:

Notes: