Geocronite Mineral Data

Geocronite Mineral Data +

General Geocronite Information

Chemical Formula:

Pb14(Sb,As)6S23

Composition:

Molecular Weight = 4,321.99 gm

Antimony 14.08 % Sb

Arsenic 1.73 % As

Lead 67.12 % Pb

Sulfur 17.06 % S

______

100.00 %

Empirical Formula:

Pb₁₄Sb₅AsS₂₃

Environment:

Hydrothermal veins with sulfides and other sulfosalt minerals.

IMA Status:

Valid Species (Pre-IMA) 1839

Locality:

Meredo, Galicia, Spain. Kilbricken Co.., Clare, Ireland. Link to MinDat.org Location Data.

Name Origin:

From the Greek for "Earth" and "Saturn", the alchemistic name for lead.

Synonym:

ICSD 41808

Kilbrickenite

PDF 43-1474

Geocronite Image

Images:

Geocronite

Comments: Many black geocronite crystals intergrown in milky quartz(?) matrix.
Location: Sala Silver Mine, Sala, V?stmanland, Sweden. Scale: 17x17x12 mm.
© John Betts - Fine Minerals

Geocronite Crystallography

Axial Ratios:

a:b:c =0.2807:1:0.2662

Cell Dimensions:

a = 8.963, b = 31.93, c = 8.5, Z = 2; beta = 118.02° V = 2,147.46 Den(Calc)= 6.68

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): 3.537(1), 3.056(0.97), 2.8897(0.96),

Forms:

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Forms: [ 2 2 5] [ 2 2 5] [ 0 1 1] [ 0 0 1]

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Crystal Structure:

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Birnie R W , Burnham C W , American Mineralogist , 61 (1976) p.963-970, The crystal structure and extent of solid solution of geocronite

Physical Properties of Geocronite

Cleavage:

[011] Distinct

Color:

Blue gray, Gray, Silver white.

Density:

6.4

Diaphaniety:

Opaque

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

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

Hardness:

2.5-3 - Finger Nail-Calcite

Luster:

Metallic

Streak:

lead gray

Optical Properties of Geocronite

RL Anisotrophism:

Moderate.

RL Color:

Pure white.

RL Pleochroism:

Weak.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Geocronite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	44.70	44.80
420 nm	43.50	44.00
440 nm	42.30	43.20
460 nm	41.30	42.30
480 nm	40.50	41.60
500 nm	39.90	41.00
520 nm	39.30	40.50
540 nm	38.80	40.10
560 nm	38.40	39.70
580 nm	38.10	39.30
600 nm	37.80	39.00
620 nm	37.40	38.50
640 nm	37.00	38.10
660 nm	36.50	37.60
680 nm	36.00	37.00
700 nm	35.40	36.30

**Calculated Relative Intensity Colors of Geocronite in Air**
Relative Intensity	0%	30%	60%	90%	100%	120%	150%	180%	210%	240%
R₁
R₂

Calculated Properties of Geocronite

Electron Density:

r_electron=5.58 gm/cc
note: r_Geocronite=6.68 gm/cc.

Fermion Index

Fermion Index = 0.1496
Boson Index = 0.8504

Photoelectric:

PE_Geocronite=1,286.21 barns/electron
U=PE_Geocronite x r_electron=7,172.53 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Geocronite is Not Radioactive

Geocronite Classification

Dana Class:

3.3.1.2 (3)Sulfides - Sulfosalts

(3.3)where 3 < z/y < 4 - (A+)i (A++)j [By Cz], A=metals, B=semi-metals, C=non-metals

(3.3.1)Dana Group

3.3.1.1 Jordanite Pb14(As,Sb)6S23 P 2₁/m 2/m

3.3.1.2 Geocronite Pb14(Sb,As)6S23 P 2₁/m 2/m

Strunz Class:

II/E.15-20 II - Sulfides and sulphosalts

II/E - Sulfosalts (S : As,Sb,Bi = x) Lead-Sulfosalts with Arsen and Antimon x = 3.8 - 3.1

II/E.15 - Jordanite - Lengenbachite series

II/E.15-10 Jordanite Pb14(As,Sb)6S23 P 2₁/m 2/m

II/E.15-20 Geocronite Pb14(Sb,As)6S23 P 2₁/m 2/m

II/E.15-30 Gratonite Pb9As4S15 R 3m 3m

II/E.15-40 Meneghinite Pb13CuSb7S24 Pbnm 2/m 2/m 2/m

II/E.15-45 Tsugaruite! Pb4As2S7 Pba2 or Pbam Ortho

II/E.15-50 Lengenbachite Pb6(Ag,Cu)2As4S13 P1 or P1 Tri

Other Geocronite Information

References:

NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)

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Geocronite

Pb14(Sb,As)6S23
Dana No: 3.3.1.2 Strunz No: II/E.15-20
Locality:

Notes: