Graeserite Mineral Data

Graeserite Mineral Data +

General Graeserite Information

Chemical Formula:

(Fe+++,Ti)4Ti3AsO13(OH)

Composition:

Molecular Weight = 666.95 gm

Titanium 21.54 % Ti 35.93 % TiO₂

Iron 33.49 % Fe 47.89 % Fe₂O₃

Arsenic 11.23 % As 14.83 % As₂O₃

Hydrogen 0.15 % H 1.35 % H₂O

Oxygen 33.58 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe³⁺₄Ti₃AsO₁₃(OH)

Environment:

The Fe++ dominant analog of tomichite and the As+++ dominant analog of derbylite. In hydrothermal veins in a two-mica paragneiss.

IMA Status:

Approved IMA 1998 (Dana # Added)

Locality:

Larchelitini, in the Monte Leone Nappe, Binntal region, western Alps, Switzerland. Link to MinDat.org Location Data.

Name Origin:

For Prof. Dr. Stefan Graeser (1935-), in recognition of his extensive research on the oxides and sulfosalts of arsenic in the Binntal region of Switzerland.

Synonym:

ICSD 50374

IMA1996-010

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Graeserite Crystallography

Axial Ratios:

a:b:c =0.5027:1:0.3503

Cell Dimensions:

a = 7.184, b = 14.289, c = 5.006, Z = 2; beta = 105.17° V = 495.97 Den(Calc)= 4.47

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: A2/m

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

By Intensity(I/I_o): 2.681(1), 2.846(0.8), 1.5825(0.5),

Physical Properties of Graeserite

Cleavage:

[100] Distinct

Color:

Black.

Density:

4.62

Diaphaniety:

Opaque

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

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

Hardness:

5.5 - Knife Blade

Luster:

Metallic

Streak:

black

Optical Properties of Graeserite

Optical Data:

NCalc= 2.48 - from Gladstone-Dale relationship (KC = 0.3315) where Ncalc=Dcalc*KC+1
NCalc= 2.53 - from Gladstone-Dale relationship (KC = 0.3315) where Ncalc=Dmeas*KC+1

Calculated Properties of Graeserite

Electron Density:

r_electron=4.24 gm/cc
note: r_Graeserite=4.47 gm/cc.

Fermion Index

Fermion Index = 0.0351
Boson Index = 0.9649

Photoelectric:

PE_Graeserite= 21.57 barns/electron
U=PE_Graeserite x r_electron= 91.37 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Graeserite is Not Radioactive

Graeserite Classification

Dana Class:

46.2.3.3 (46)Basic or Halogen-Containing Antimonites, Arsenites and Phosphites

(46.2)with miscellaneous formulae

(46.2.3)Derbylite Group

46.2.3.1 Tomichite (V,Fe)4Ti3AsO13(OH) A2/m 2/m

46.2.3.2 Derbylite (Fe,Fe,Ti)7SbO13(OH) P 2₁/m 2/m

46.2.3.3 Graeserite ! (Fe,Ti)4Ti3AsO13(OH) A2/m 2/m

Strunz Class:

IV/C.23-15 IV - Oxides

IV/C - Oxides with metal : oxygen = 2:3 (M2O3 and related compounds)

IV/C.23 - Hemloite - Derbylite series

IV/C.23-10 Hemloite (As,Sb)2(Ti,V,Fe,Al)12O23OH P1 1

IV/C.23-15 Graeserite (Fe,Ti)4Ti3AsO13(OH) A2/m 2/m

IV/C.23-20 Tomichite (V,Fe)4Ti3AsO13(OH) A2/m 2/m

IV/C.23-30 Derbylite (Fe,Fe,Ti)7SbO13(OH) P 2₁/m 2/m

Other Graeserite Information

References:

NAME( MinRec) PHYS. PROP.(MinRec)

See Also:

Links to other databases for Graeserite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -Handbook of Mineralogy (UofA) 6 -MinDAT 7 -MinMax(Deutsch) 8 -MinMax(English) 9 -Mineralienatlas (Deutsch) 10 -QUT Mineral Atlas

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Graeserite

(Fe+++,Ti)4Ti3AsO13(OH)
Dana No: 46.2.3.3 Strunz No: IV/C.23-15
Locality:

Notes: