Mineralogy Database

Fornacite Mineral Data

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General Fornacite Information

Help on Chemical  Formula: Chemical Formula: Pb2Cu(CrO4)(AsO4)(OH)
Help on Composition: Composition: Molecular Weight = 749.87 gm
   Chromium   6.93 %  Cr   13.33 % CrO3
   Copper     8.47 %  Cu    9.54 % Cu2O
   Arsenic    9.99 %  As   15.33 % As2O5
   Hydrogen   0.13 %  H     1.20 % H2O
   Lead      55.26 %  Pb   59.53 % PbO
   Oxygen    19.20 %  O
            ______        ______ 
            100.00 %       98.93 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Pb2Cu(AsO4)(CrO4)(OH)
Help on Environment: Environment: Oxidized zones of some hydrothermal base-metal deposits.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1915
Help on Locality: Locality: Djoue and Reneville, Congo Republic. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Lucien Lewis Forneau (1867-1930), Colonial Governor of the French Congo.
Help on Name Pronunciation: Name Pronunciation: Fornacite + Pronunciation Say FORNACITE
Help on Synonym: Synonym: ICSD 26828
  PDF 15-200

Fornacite Image

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Comments: Dark, prismatic crystals of fornacite on matrix.
Location: El Khun mine, Anarak, Iran. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

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Comments: Emerald green platy crystals to 0.75mm on a pink to white, siliceous matrix.
Location: Lone Star mine, Copperopolis, Yavapai County, Arizona. Scale: Picture size 1.4 cm.
© Tom Loomis / Dakota Matrix

Fornacite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =1.3384:1:2.9543
Help on Cell Dimensions: Cell Dimensions: a = 7.91, b = 5.91, c = 17.46, Z = 4; beta = 108° V = 776.27 Den(Calc)= 6.42
Help on Crystal System: Crystal System: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 21/c
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.88(1), 2.98(1), 3.31(1),

Physical Properties of Fornacite

Help on Cleavage: Cleavage: None
Help on Color: Color: Green, Yellow, Olive green, Greenish yellow.
Help on Density: Density: 6.27
Help on Diaphaneity: Diaphaneity: Transparent to Translucent
Help on Fracture: Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Help on Habit: Habit: Aggregates - Made of numerous individual crystals or clusters.
Help on Hardness: Hardness: 2-3 - Gypsum-Calcite
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: greenish yellow

Optical Properties of Fornacite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.084 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.059 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1854,KPDmeas= 0.1898,KC= 0.1751
Ncalc = 2.1 - 2.12
Help on Optical Data: Optical Data: Biaxial (+), a=2.14, g=2.24, bire=0.1000, 2V(Meas)=large.

Calculated Properties of Fornacite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=5.53 gm/cc
note: Specific Gravity of Fornacite =6.42 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.12
Boson Index = 0.88
Help on Photoelectric: Photoelectric: PEFornacite = 998.15 barns/electron
U=PEFornacite x rElectron Density=5,520.53 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Fornacite is Not Radioactive

Fornacite Classification

Help on  Dana Class: Dana Class: (43)Compound Phosphates, etc.
  (43.04)(Anhydrous Compound Anions With Hydroxyl or Halogen)
  (43.04.03)Vauquelinite Group Vauquelinite Pb2Cu(CrO4)(PO4)(OH) P 21/n 2/m Fornacite Pb2Cu(CrO4)(AsO4)(OH) P 21/c 2/m Molybdofornacite Pb2Cu[(As,P)O4][(Mo,Cr)O4](OH) P 21/c 2/m
Help on  Strunz Class: Strunz Class: 07.FC.10 07 - SULFATES (SELENATES, TELLURATES)
  07.F - Chromates
  07.FC -With PO4, AsO4, SiO4
07.FC.10 Fornacite Pb2Cu(CrO4)(AsO4)(OH) P 21/c 2/m
07.FC.10 Molybdofornacite Pb2Cu[(As,P)O4][(Mo,Cr)O4](OH) P 21/c 2/m

Other Fornacite Information

Help on References: References: NAME( AntBidBlaNic4) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic4)
Help on See Also: See Also: Links to other databases for Fornacite :
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: 07.FC.10





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