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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:
PEBarstowite =1,354.95 barns/electron U=PEBarstowite x rElectron Density=6,564.29 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Barstowite is Not Radioactive