Mineralogy Database

Geminite Mineral Data

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General Geminite Information

Help on Chemical  Formula: Chemical Formula: Cu++2As+++++2O7•3(H2O)
Help on Composition: Composition: Molecular Weight = 442.98 gm
   Copper    28.69 %  Cu   35.91 % CuO
   Arsenic   33.83 %  As   51.89 % As2O5
   Hydrogen   1.37 %  H    12.20 % H2O
   Oxygen    36.12 %  O
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Cu2As2O7•3(H2O)
Help on Environment: Environment: Coatings on quartz.
Help on IMA Status: IMA Status: Approved IMA 1990
Help on Locality: Locality: Cap Garonne mine, Var, France. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named from the Latin gemini, twins, in allusion to the usual character of the crystals.
Help on Name Pronunciation: Name Pronunciation: Geminite Say GEMINITE
Help on Synonym: Synonym: ICSD 81587
  PDF 44-1454

Geminite Image

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Comments: Pale greenish crystals of geminite with a light blue, lavendulane-related mineral.
Location: Shaft 371, Schlema-Hartenstein area, Erzgebirge, Saxony, Germany. Scale: Picture size 4 mm.
© Thomas Witzke / Abraxas-Verlag

Geminite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.8186:1:1.9398
Help on Cell Dimensions: Cell Dimensions: a = 6.639, b = 8.11, c = 15.732, Z = 4; alpha = 92.01°, beta = 93.87°, gamma = 95.02° V = 841.36 Den(Calc)= 3.50
Help on Crystal System: Crystal System: Triclinic Space Group: P1 or P1
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 7.83(1), 3.07(0.7), 3.26(0.7),

Physical Properties of Geminite

Help on Cleavage: Cleavage: {001} Perfect
Help on Color: Color: Light green, Sea green.
Help on Density: Density: 3.7 - 3.71, Average = 3.7
Help on Diaphaneity: Diaphaneity: Transparent
Help on Fracture: Fracture: Irregular - Flat surfaces (not cleavage) fractured in an irregular pattern.
Help on Habit: Habit: Columnar - Forms columns
Help on Habit: Habit: Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)
Help on Habit: Habit: Twinning Common - Crystals are usually twinned.
Help on Hardness: Hardness: 3-3.5 - Calcite-Copper Penny
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous (Glassy)
Help on Magnetism: Magnetism: Nonmagnetic
Help on Streak: Streak: pale green

Optical Properties of Geminite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.021 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.081 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2017,KPDmeas= 0.1906,KC= 0.1866
Ncalc = 1.65 - 1.69
Help on Optical Data: Optical Data: Biaxial (+), a=1.656, b=1.692, g=1.77, bire=0.1140, 2V(Calc)=72, 2V(Meas)=75. Dispersion weak, r > v.
Help on Pleochroism (x): Pleochroism (x): colorless.
Help on Pleochroism (y): Pleochroism (y): colorless.
Help on Pleochroism (z): Pleochroism (z): green pale grayish.

Calculated Properties of Geminite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.51 gm/cc
note: Specific Gravity of Geminite =3.71 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0001754138
Boson Index = 0.9998245862
Help on Photoelectric: Photoelectric: PEGeminite = 35.88 barns/electron
U=PEGeminite x rElectron Density= 126.04 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Geminite is Not Radioactive

Geminite Classification

Help on  Dana Class: Dana Class: (40)Hydrated Phosphates, etc
  (40.05)with miscellaneous formulae
  (40.05.12)Dana Group Geminite Cu2As2O7•3(H2O) P1 or P1 Tri Pushcharovskite! Cu(AsO3OH)•1.5(H2O) P1 or P1 Tri
Help on  Strunz Class: Strunz Class: 08.CB.30 08 - PHOSPHATES, ARSENATES, VANADATES
  08.C - Phosphates without Additional Anions, with H2O
  08.CB -With only medium-sized cations, RO4:H2O = 1:1
08.CB.30 Geminite Cu2As2O7•3(H2O) P1 or P1 Tri

Other Geminite Information

Help on References: References: NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Dana8)
Help on See Also: See Also: Links to other databases for Geminite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Dana No: Strunz No: 08.CB.30





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