Barstowite Mineral Data

General Barstowite Information

Chemical Formula:

Pb4(CO3)Cl6•(H2O)

Composition:

Molecular Weight = 1,119.54 gm

Hydrogen 0.18 % H 1.61 % H₂O

Lead 74.03 % Pb 79.75 % PbO

Carbon 1.07 % C 3.93 % CO₂

Chlorine 19.00 % Cl 19.00 % Cl

- % Cl -4.29 % -O=Cl₂

Oxygen 5.72 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Pb₄(CO₃)Cl₆•(H₂O)

Environment:

Quartz-dolomite ore vein exposed to sea water at the base of the cliff.

IMA Status:

Approved IMA 1991

Locality:

Bounds Cliff, St. Endellion, Cornwall, England. Link to MinDat.org Location Data.

Name Origin:

Named for Richard William Barstow (1947-1982), Cornish mineral dealer.

Name Pronunciation:

Barstowite + Pronunciation

Synonym:

ICSD 411366

IMA1989-057

PDF 51-1520

Barstowite Image

Images:

Barstowite

Comments: SEM images of irregular prismatic barstowite with phosgenite. (MinMag, v55:378).
Location: Lead-antimony vein at the southwestern end of Bounds Cliff, St Endellion, Cornwall, UK. Scale: Scale bar left 400 µm right 100 µm.
© Mineralogical Magazine

Barstowite Crystallography

Axial Ratios:

a:b:c =0.457:1:1.8113

Cell Dimensions:

a = 4.2043, b = 9.199, c = 16.663, Z = 2; beta = 91.82° V = 644.12 Den(Calc)= 5.77

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/m

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

By Intensity(I/I_o): 4.02(1), 2.296(0.8), 2.377(0.6),

Crystal Structure:

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drag2 - RMB Resize/Rotate
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Steele I M , Pluth J J , Stanley C J , Mineralogical Magazine , 63 (1999) p.901-907, Crystal structure of barstowite (3PbCl2PbCO3H2O), Locality: Bounds Cliff, St Endellion, Cornwall

Physical Properties of Barstowite

Cleavage:

{???} Indistinct

Color:

Colorless, White.

Density:

5.5 - 5.69, Average = 5.59

Diaphaneity:

Transparent to Opaque

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Microscopic Crystals - Crystals visible only with microscopes.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

3 - Calcite

Luster:

Adamantine

Streak:

white

Optical Properties of Barstowite

Optical Data:

Biaxial (?)

NCalc= 2.04 - from Gladstone-Dale relationship (KC = 0.1799) where Ncalc=Dcalc*KC+1
NCalc= 2.01 - from Gladstone-Dale relationship (KC = 0.1799) where Ncalc=Dmeas*KC+1

RL Anisotrophism:

Weak to moderate.

RL Bireflectance:

Moderate, gray to dark gray.

RL Color:

White with abundant colorless internal reflections.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Barstowite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	14.20	14.80
420 nm	14.00	14.60
440 nm	13.80	14.40
460 nm	13.70	14.10
480 nm	13.40	13.90
500 nm	13.20	13.70
520 nm	13.10	13.50
540 nm	12.90	13.40
560 nm	12.80	13.20
580 nm	12.70	13.10
600 nm	12.60	13.00
620 nm	12.50	12.90
640 nm	12.50	12.90
660 nm	12.40	12.80
680 nm	12.30	12.80
700 nm	12.30	12.70

**Calculated Relative Intensity Colors of Barstowite in Air**
Relative Intensity	0%	70%	100%	140%	210%	280%	350%	420%	490%	560%	630%	690%
R₁
R₂

Calculated Properties of Barstowite

Electron Density:

Bulk Density (Electron Density)=4.84 gm/cc
note: Specific Gravity of Barstowite =5.77 gm/cc.

Fermion Index:

Fermion Index = 0.16
Boson Index = 0.84

Photoelectric:

PE_Barstowite=1,354.95 barns/electron
U=PE_Barstowite x rElectron Density=6,564.29 barns/cc.

Radioactivity:

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

Barstowite Classification

Dana Class:

12.01.07.01 (12)Compound Halides

(12.01)with miscellaneous anions

(12.01.07)Dana Group

12.01.07.01 Barstowite Pb4(CO3)Cl6•(H2O) P 2₁/m 2/m

Strunz Class:

03.DC.95 03 - HALIDES

03.D - Oxyhalides, Hydroxyhalides and Related Double Halides

03.DC -With Pb (As,Sb,Bi), without Cu

03.DC.95 Barstowite Pb4(CO3)Cl6•(H2O) P 2₁/m 2/m

Other Barstowite Information

References:

NAME( Dana8) PHYS. PROP.(AmMin, vol 86) OPTIC PROP.(AntBidBlaNic5)

See Also:

Links to other databases for Barstowite :
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
15 - WWW-MINCRYST

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Ask about Barstowite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
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Rockhounds Discussion Group on Yahoo Groups
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Print or Cut-and-Paste your Barstowite Specimen Label here :

Barstowite

Pb4(CO3)Cl6•(H2O)
Dana No: 12.01.07.01 Strunz No: 03.DC.95
Locality:

Notes: