Melanocerite-(Ce) Mineral Data

Melanocerite-(Ce) Mineral Data +

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General Melanocerite-(Ce) Information

Chemical Formula:

(Ce,Th,Ca)5(Si,B)3O12(OH,F)·n(H2O) (?)

Composition:

Molecular Weight = 903.06 gm

Calcium 4.88 % Ca 6.83 % CaO

Lanthanum 10.77 % La 12.63 % La₂O₃

Cerium 46.55 % Ce 54.52 % Ce₂O₃

Thorium 5.14 % Th 5.85 % ThO₂

Silicon 6.22 % Si 13.31 % SiO₂

Boron 1.20 % B 3.85 % B₂O₃

Hydrogen 0.28 % H 2.49 % H₂O

Oxygen 23.92 % O

Fluorine 1.05 % F 1.05 % F

- % F -0.44 % -O=F₂

______ ______

100.00 % 100.09 % = TOTAL OXIDE

Empirical Formula:

Ce₃La_0.7Th_0.2Ca_1.1Si₂BO₁₂(OH)_0.5F_0.5·(H₂O)

Environment:

Alkalic rocks and their cogenetic pegmatites. Also in metamorphosed alkalic rocks.

IMA Status:

Valid Species (Pre-IMA) 1887

Locality:

Isle of Kjeo in the Langesundfiord district, southern Norway. Link to MinDat.org Location Data.

Name Origin:

Named from the Greek meaning "black" and the composition (Cerium).

Melanocerite-(Ce) Image

Images:

Melanocerite-(Ce)

Comments: Black, vitreous, crystalline aggregates of melanocerite-(Ce) in matrix.
Location: Cardiff Uranium mine, Wilberforce, Monmouth Township, Haliburton Co., Ontario, Canada. Scale: See Image.
© Paul M. Schumacher

Melanocerite-(Ce) Crystallography

Axial Ratios:

a:c = 1:0.73582

Cell Dimensions:

a = 9.35, c = 6.88, Z = 2; V = 520.89 Den(Calc)= 5.76

Crystal System:

TrigonalSpace Group: Unk (HEX-R)

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

By Intensity(I/I_o): 2.81(1), 1.84(0.4), 3.44(0.4),

Physical Properties of Melanocerite-(Ce)

Cleavage:

None

Color:

Brown, Black, Dark brown, Reddish brown.

Density:

4.13

Diaphaniety:

Subtransparent to opaque

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Metamict - Mineral originally crystalline, now amorphous due to radiation damage.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

5-6 - Between Apatite and Orthoclase

Luminescence:

Radioactive.

Luster:

Resinous

Streak:

light brown

Optical Properties of Melanocerite-(Ce)

Gladstone-Dale:

CI meas= -0.056 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.243 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1259,KPDmeas= 0.1755,KC= 0.1662

Optical Data:

Uniaxial (-), e=1.72, w=1.73, bire=0.0100.

Calculated Properties of Melanocerite-(Ce)

Electron Density:

r_electron=3.68 gm/cc
note: r_{Melanocerite-(Ce)}=4.13 gm/cc.

Fermion Index

Fermion Index = 0.00556
Boson Index = 0.99444

Photoelectric:

PE_{Melanocerite-(Ce)}= 415.84 barns/electron
U=PE_{Melanocerite-(Ce)} x r_electron=1,528.65 barns/cc.

Radioactivity:

GRapi = 97,579.37 (Gamma Ray American Petroleum Institute Units)

Melanocerite-(Ce) is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.

Estimated Maximum U.S. Postal Shipping Size (10 mRem/hr limit, Unshielded 10 cm box) 311.71 ± 77.93 grams of pure Melanocerite-(Ce) .

**Estimated Radioactivity from Melanocerite-(Ce)** - weak
Specimen Size Weight/Volume (Sphere) *	Calculated Activity Bequerols (Bq)	Calculated Activity Curies (Ci)	Estimated Activity GR(api)	Estimated Exposure (mRem**)/hr If Held in Hand For One Hour
1000 gm / 7.73 cm	2,302,227	6.22E-05	97,579.37	32.08
100 gm / 3.59 cm	230,223	6.22E-06	9,757.94	3.21
10 gm / 1.67 cm	23,022	6.22E-07	975.79	0.32
1 gm / 7.73 mm	2,302	6.22E-08	97.58	0.03
0.1 gm / 3.59 mm	230	6.22E-09	9.76	0.00
0.01 gm / 1.67 mm	23	6.22E-10	0.98	0.00
0.001 gm / 0.77 mm	2	6.22E-11	0.10	0.00

Weight of pure Melanocerite-(Ce) in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.13 gm/cc.*
Goverment Estimate of Average Annual Exposure ( 360 mRem) **
Note: 10 microsieverts/hr = 1 mRem/hr **
Max Permissable Adult Dose 50,000 mRem/yr (hands), 15,000 mRem/yr (eyes)
Lethal Dose LD(50) Exposure 400,000 to 500,000 mRem

Melanocerite-(Ce) Classification

Dana Class:

54.2.5.3 (54)Nesosilicate Borosilicates and Some Beryllosilicates

(54.2)with B in [4] coordination

(54.2.5)Tritomite group

54.2.5.1 Tritomite-(Ce) (Ce,La,Ca,Y,Th)5(Si,B)3(O,OH,F)13 P 6₃/m 6/m

54.2.5.2 Tritomite-(Y) (Y,Ca,La,Fe)5(Si,B,Al)3(O,OH,F)13(?) P 6₃/m 6/m

54.2.5.3 Melanocerite-(Ce) (Ce,Th,Ca)5(Si,B)3O12(OH,F)·n(H2O)(?) Unk (HEX-R) Trig

Strunz Class:

VIII/B.33-10 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, with beryllium and boron

VIII/B.33 - Melanocerite-(Ce) - Tritomite-(Ce) series

VIII/B.33-10 Melanocerite-(Ce) (Ce,Th,Ca)5(Si,B)3O12(OH,F)·n(H2O)(?) Unk (HEX-R) Trig

VIII/B.33-20 Okanoganite-(Y) (Na,Ca)3(Y,Ce)12Si6B2O27F14 R 3m 3m

VIII/B.33-25 Vicanite-(Ce) (Ca,Ce,La,Th)15As(As0.5,Na0.5)FeSi6B4O40F7 R 3m 3m

VIII/B.33-30 Tritomite-(Y) (Y,Ca,La,Fe)5(Si,B,Al)3(O,OH,F)13(?) P 6₃/m 6/m

VIII/B.33-40 Tritomite-(Ce) (Ce,La,Ca,Y,Th)5(Si,B)3(O,OH,F)13 P 6₃/m 6/m

Other Melanocerite-(Ce) Information

References:

NAME( Ford32) PHYS. PROP.(Dana8) OPTIC PROP.(Ford32)

See Also:

Links to other databases for Melanocerite-(Ce) :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (MinSocAm) 7 -Handbook of Mineralogy (UofA) 8 -MinDAT 9 -MinMax(Deutsch) 10 -MinMax(English) 11 -Mineralienatlas (Deutsch) 12 -QUT Mineral Atlas

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Melanocerite-(Ce)

(Ce,Th,Ca)5(Si,B)3O12(OH,F)·n(H2O) (?)
Dana No: 54.2.5.3 Strunz No: VIII/B.33-10
Locality:

Notes: