Crocoite Mineral Data

General Crocoite Information

Chemical Formula:

PbCrO4

Composition:

Molecular Weight = 323.19 gm

Chromium 16.09 % Cr 30.94 % CrO₃

Lead 64.11 % Pb 69.06 % PbO

Oxygen 19.80 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

PbCrO₄

Environment:

Secondary mineral of oxidized lead veins infiltrated by Cr bearing fluids..

IMA Status:

Valid Species (Pre-IMA) 1832

Locality:

Tasmania. Link to MinDat.org Location Data.

Name Origin:

From the Greek krokos, meaning "crocus" or "saffron."

Name Pronunciation:

Crocoite

Synonym:

Bellite - a mixture of quartz, mimetite and crocoite, or simply Cr-bearing mimetite

ICSD 24607

PDF 8-209

Red Lead Ore

Crocoite Image

Images:

Crocoite

Comments: Prismatic crystals of red-orange crocoite.
Location: Adelaide Mine, Dundas, Tasmania. Scale: Specimen size 5 cm.
© Dave Barthelmy

Images:

Vauquelinite Crocoite

Comments: Olive-greenish vauquelinite encrusting red crocoite.
Location: Callenberg North (no. 1) open cut, Callenberg, Glauchau, Saxony, Germany. Scale: Picture size 6 mm.
© Thomas Witzke / Abraxas-Verlag

Images:

Coronadite Crocoite

Comments: Black coronadite with red crocoite on matrix.
Location: Callenberg North (no. 1) open cut, Callenberg, Glauchau, Saxony, Germany. Scale: Specimen size 7 cm.
© Thomas Witzke / Abraxas-Verlag

Crocoite Crystallography

Axial Ratios:

a:b:c =0.9569:1:0.9139

Cell Dimensions:

a = 7.12, b = 7.44, c = 6.8, Z = 4; beta = 77.55° V = 351.74 Den(Calc)= 6.10

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2₁/n

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

By Intensity(I/I_o): 3.28(1), 3.03(0.65), 3.48(0.55),

Forms:

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Forms: ( 0 1 0) ( 1 0 1) ( 1 1 0) ( 1 1 1) ( 0 0 1)

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Physical Properties of Crocoite

Cleavage:

{110} Distinct, {001} Indistinct, {100} Indistinct

Color:

Yellow, Orange, Red, Red orange.

Density:

5.9 - 6.1, Average = 6

Diaphaneity:

Translucent

Fracture:

Sectile - Curved shavings or scrapings produced by a knife blade, (e.g. graphite).

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

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

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Hardness:

2.5-3 - Finger Nail-Calcite

Luminescence:

Non-fluorescent.

Luster:

Adamantine

Streak:

yellowish orange

Optical Properties of Crocoite

Gladstone-Dale:

CI meas= -0.233 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.213 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2372,KPDmeas= 0.2411,KC= 0.1955
Ncalc = 2.15 - 2.19

Optical Data:

Biaxial (+), a=2.31, b=2.37, g=2.66, bire=0.3500, 2V(Calc)=54, 2V(Meas)=57. Dispersion none.

Pleochroism (x):

none.

Pleochroism (y):

none.

Pleochroism (z):

none.

Calculated Properties of Crocoite

Electron Density:

Bulk Density (Electron Density)=5.21 gm/cc
note: Specific Gravity of Crocoite =6.10 gm/cc.

Fermion Index:

Fermion Index = 0.15
Boson Index = 0.85

Photoelectric:

PE_Crocoite=1,156.55 barns/electron
U=PE_Crocoite x rElectron Density=6,024.79 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Crocoite is Not Radioactive

Crocoite Classification

Dana Class:

35.03.01.01 (35)Anhydrous Chromates

(35.03)where A+ XO4

(35.03.01)Dana Group

35.03.01.01 Crocoite PbCrO4 P 2₁/n 2/m

Strunz Class:

07.FA.20 07 - SULFATES (SELENATES, TELLURATES)

07.F - Chromates

07.FA -Without additional anions

07.FA.20 Crocoite PbCrO4 P 2₁/n 2/m

Other Crocoite Information

References:

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

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Print or Cut-and-Paste your Crocoite Specimen Label here :

Crocoite

PbCrO4
Dana No: 35.03.01.01 Strunz No: 07.FA.20
Locality:

Notes:

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