Mineralogy Database

Lopezite Mineral Data

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General Lopezite Information

Help on Chemical  Formula: Chemical Formula: K2Cr2O7
Help on Composition: Composition: Molecular Weight = 294.18 gm
   Potassium  26.58 %  K    32.02 % K2O
   Chromium   35.35 %  Cr   67.98 % CrO3
   Oxygen     38.07 %  O
             ______        ______ 
             100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: K2Cr2O7
Help on Environment: Environment: Rare secondary mineral in vugs in massive nitrate rock.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1937
Help on Locality: Locality: In Chile, in Tarapaca, from Oficina Rosario, Huara, Pampa del Iquique; Oficina Maria Elena, near Tocopilla, Pampa del Tocopilla; and at Zapiga. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Emiliano Lopez Saa (1871-1959), Iquique, Chile, Chilean mining engineer and mineral collector long associated with the Chilean nitrate industry.
Help on Name Pronunciation: Name Pronunciation: Lopezite Say LOPEZITE
Help on Synonym: Synonym: ICSD 10371
  PDF 27-380

Lopezite Image

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Comments: yellowish granular lopezite.
Location: Tarapaca, Chile. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Lopezite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.5597:1:0.5507
Help on Cell Dimensions: Cell Dimensions: a = 7.5, b = 13.4, c = 7.38, Z = 4; alpha = 98°, beta = 90.85°, gamma = 96.217° V = 730.07 Den(Calc)= 2.68
Help on Crystal System: Crystal System: Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 3.32(1), 3.49(0.3), 3.68(0.2),

Physical Properties of Lopezite

Help on Cleavage: Cleavage: {010} Perfect, {100} Distinct, {001} Distinct
Help on Color: Color: Orange red, Red.
Help on Density: Density: 2.69
Help on Diaphaneity: Diaphaneity: Transparent
Help on Hardness: Hardness: 2.5 - Finger Nail
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: light yellow

Optical Properties of Lopezite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.04 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.036 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.28,KPDmeas= 0.2789,KC= 0.2905
Ncalc = 1.78
Help on Optical Data: Optical Data: Biaxial (+), a=1.714, b=1.732, g=1.805, bire=0.0910, 2V(Calc)=56, 2V(Meas)=50.

Calculated Properties of Lopezite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.59 gm/cc
note: Specific Gravity of Lopezite =2.68 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.03
Boson Index = 0.97
Help on Photoelectric: Photoelectric: PELopezite = 10.72 barns/electron
U=PELopezite x relectron= 27.75 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 370.25 (Gamma Ray American Petroleum Institute Units)
Concentration of Lopezite per GRapi unit = 0.27 (%)

Estimated Radioactivity from Lopezite - barely detectable


Lopezite Classification

Help on  Dana Class: Dana Class: (35)Anhydrous Chromates
  (35.02)where (A+)2 X2O7
  (35.02.01)Dana Group Lopezite K2Cr2O7 P1 1
Help on  Strunz Class: Strunz Class: 07.FD.05 07 - SULFATES (SELENATES, TELLURATES)
  07.F - Chromates
  07.FD -Dichromates
07.FD.05 Lopezite K2Cr2O7 P1 1

Other Lopezite Information

Help on References: References: NAME( AntBidBlaNic4) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: See Also: Links to other databases for Lopezite :
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.FD.05





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