Pharmacosiderite Mineral Data

Pharmacosiderite Mineral Data +

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General Pharmacosiderite Information

Chemical Formula:

KFe+++4(AsO4)3(OH)4·6-7(H2O)

Composition:

Molecular Weight = 873.38 gm

Potassium 4.48 % K 5.39 % K₂O

Iron 25.58 % Fe 36.57 % Fe₂O₃

Arsenic 25.74 % As 39.47 % As₂O₅

Hydrogen 2.08 % H 18.56 % H₂O

Oxygen 42.13 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

KFe³⁺₄(AsO₄)₃(OH)₄·7(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1813

Locality:

Link to MinDat.org Location Data.

Name Origin:

From the Greek, farmakon for "poison" and sideros for "iron."

Synonym:

ICSD 27302

PDF 34-155

Pharmacosiderite Image

Images:

Click Here for Larger Pharmacosiderite Image

Pharmacosiderite Arthurite

Comments: Altered rhyolite vug lined with brilliant apple green arthurite and cubic green crystals of pharmacosiderite.
Location: Majuba Hill Mine, Pershing County, Nevada. USA. Scale: 2.7 x 1.7 cm.
© John Veevaert

Images:

Pharmacosiderite

Comments: Translucent yellow-brown cubic Pharmacosiderite crystals.
Location: Wheal Gorland, Saint Day, Cornwall, England. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Pharmacosiderite Crystallography

Cell Dimensions:

a = 15.961, Z = 8; V = 4,066.12 Den(Calc)= 2.85

Crystal System:

Isometric - HextetrahedralH-M Symbol (4 3m) Space Group: I 43m

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

By Intensity(I/I_o): 4.61(1), 8(0.9), 2.408(0.8),

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Crystal Structure:

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Buerger M J , Dollase W A , Garaycochea-Wittke I , Zeitschrift fur Kristallographie , 125 (1967) p.92-108, The structure and composition of the mineral pharmacosiderite, Note: the K atom could not be located, Locality: Cornwall, England

Physical Properties of Pharmacosiderite

Cleavage:

[100] Indistinct

Color:

Olive green, Emerald green, Reddish brown, Yellowish brown, Honey yellow.

Density:

2.8 - 3, Average = 2.9

Diaphaniety:

Subtransparent to subtranslucent

Fracture:

Brittle - Sectile - Brittle fracture with slightly sectile shavings possible.

Habit:

Blocky - Crystal shape tends to be equant (e.g. feldspars).

Habit:

Crystalline - Coarse - Occurs as well-formed coarse sized crystals.

Habit:

Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).

Hardness:

2.5 - Finger Nail

Luminescence:

None.

Luster:

Adamantine - Resinous

Streak:

yellowish green

Optical Properties of Pharmacosiderite

Gladstone-Dale:

CI meas= 0.055 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.038 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2432,KPDmeas= 0.239,KC= 0.2528

Optical Data:

Isotropic, n=1.693.

Calculated Properties of Pharmacosiderite

Electron Density:

r_electron=2.77 gm/cc
note: r_{Pharmacosiderite}=2.85 gm/cc.

Fermion Index

Fermion Index = 0.00563
Boson Index = 0.99437

Photoelectric:

PE_{Pharmacosiderite}= 25.35 barns/electron
U=PE_{Pharmacosiderite} x r_electron= 70.15 barns/cc.

Radioactivity:

GRapi = 62.69 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Pharmacosiderite - barely detectable

Pharmacosiderite Classification

Dana Class:

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

(42.8)where (AB)7 (XO4)4 Zq · x(H2O)

(42.8.1)Dana Group

42.8.1.1 Pharmacosiderite KFe4(AsO4)3(OH)4·6-7(H2O) I 43m 4 3m

42.8.1.2 Alumopharmacosiderite KAl4(AsO4)3(OH)4·6·5(H2O) P 43m 4 3m

42.8.1.3 Barium-pharmacosiderite BaFe4(AsO4)3(OH)5·5(H2O) I 42m 4 2m

42.8.1.4 Barium-alumopharmacosiderite? BaAl4(AsO4)3(OH)5·5(H2O) P 43m ? 4 3m

42.8.1.5 Sodium-pharmacosiderite (Na,K)2Fe4(AsO4)3(OH)5·7(H2O) P 43m 4 3m

Strunz Class:

VII/D.47-20 VII - Phosphates, Arsenates and Vanadates

VII/D - Water-bearing phosphates with unfamiliar anions, cations of very big and medium size: Al, Mg and Ca, Na, K

VII/D.47 - Pharmacosiderite series

VII/D.47-10 Alumopharmacosiderite KAl4(AsO4)3(OH)4·6·5(H2O) P 43m 4 3m

VII/D.47-20 Pharmacosiderite KFe4(AsO4)3(OH)4·6-7(H2O) I 43m 4 3m

VII/D.47-30 Sodium-pharmacosiderite (Na,K)2Fe4(AsO4)3(OH)5·7(H2O) P 43m 4 3m

VII/D.47-40 Barium-alumopharmacosiderite? BaAl4(AsO4)3(OH)5·5(H2O) P 43m ? 4 3m

VII/D.47-50 Barium-pharmacosiderite BaFe4(AsO4)3(OH)5·5(H2O) I 42m 4 2m

Other Pharmacosiderite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

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Pharmacosiderite

KFe+++4(AsO4)3(OH)4·6-7(H2O)
Dana No: 42.8.1.1 Strunz No: VII/D.47-20
Locality:

Notes: