Hellandite-(Ce) Mineral Data

Hellandite-(Ce) Mineral Data +

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General Hellandite-(Ce) Information

Chemical Formula:

(Ca3REE)4Ce2Al[ ]2[Si4 B4O22](OH)2

Composition:

Molecular Weight = 1,114.02 gm

Calcium 10.79 % Ca 15.10 % CaO

Cerium 25.15 % Ce 29.46 % Ce₂O₃

La,Ce,Pr,Nd,Sm, 12.93 % RE 15.08 % REE₂O₃

Aluminum 2.42 % Al 4.58 % Al₂O₃

Silicon 10.08 % Si 21.57 % SiO₂

Boron 3.88 % B 12.50 % B₂O₃

Hydrogen 0.14 % H 1.21 % H₂O

Oxygen 33.75 % O

Fluorine 0.85 % F 0.85 % F

- % F -0.36 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₃REECe₂AlSi₄B₄O₂₂(OH)_1.5F_0.5

Environment:

Occurs in miarolitic cavities in a volcanic ejectum within an explosive breccia. (hellandite group; structure)

IMA Status:

Approved IMA 2001 (Dana # Added)

Locality:

Pyroclastic flow unit (ignibrite "C") of the Vico volcanic complex near Capranica (Viterbo Province), north of Rome, Italy. Link to MinDat.org Location Data.

Name Origin:

Named for Amund Theodor Helland (1846-1918), geologist of Oslo, Norway.

Synonym:

IMA2000-F

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Hellandite-(Ce) Crystallography

Axial Ratios:

a:b:c =4.0185:1:2.1683

Cell Dimensions:

a = 19.068, b = 4.745, c = 10.289, Z = 1; beta = 111.18° V = 868.04 Den(Calc)= 2.13

Crystal System:

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

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

By Intensity(I/I_o): 2.652(1), 2.635(0.73), 2.855(0.56),3.238(0.5), 1.905(0.49), 1.901(0.41), 2.916(0.35),

Crystal Structure:

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Oberti R , Ottolini L , Camara F , Della Ventura G , American Mineralogist , 84 (1999) p.913-921, Crystal structure of non-metamict Th-rich hellandite-(Ce) from Latium (Italy), and crystal chemistry of the hellandite-group minerals

Physical Properties of Hellandite-(Ce)

Color:

Pale brown, Light green.

Diaphaniety:

Transparent

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Habit:

Microscopic Crystals - Crystals visible only with microscopes.

Hardness:

5.5-6 - Knife Blade-Orthoclase

Luster:

Vitreous (Glassy)

Optical Properties of Hellandite-(Ce)

Gladstone-Dale:

CI calc= -0.815 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.3258,KC= 0.1795

Optical Data:

Biaxial (-), a=1.68, b=1.694, g=1.708, bire=0.0280

Calculated Properties of Hellandite-(Ce)

Electron Density:

r_electron=1.99 gm/cc
note: r_{Hellandite-(Ce)}=2.13 gm/cc.

Fermion Index

Fermion Index = 0.03679
Boson Index = 0.96321

Photoelectric:

PE_{Hellandite-(Ce)}= 204.79 barns/electron
U=PE_{Hellandite-(Ce)} x r_electron= 407.21 barns/cc.

Radioactivity:

GRapi = 37,966.66 (Gamma Ray American Petroleum Institute Units)

Hellandite-(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) 801.14 ±200.29 grams of pure Hellandite-(Ce) .

**Estimated Radioactivity from Hellandite-(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 / 9.64 cm	854,050	2.31E-05	37,966.66	12.48
100 gm / 4.48 cm	85,405	2.31E-06	3,796.67	1.25
10 gm / 2.08 cm	8,541	2.31E-07	379.67	0.12
1 gm / 9.64 mm	854	2.31E-08	37.97	0.01
0.1 gm / 4.48 mm	85	2.31E-09	3.80	0.00
0.01 gm / 2.08 mm	9	2.31E-10	0.38	0.00
0.001 gm / 0.96 mm	1	2.31E-11	0.04	0.00

Weight of pure Hellandite-(Ce) in grams (gm) and Calculated Diameter of a Sphere with a Density of 2.13 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
Estimated Thorium Activity ( 1.90 % Th) From Sum REE Elements (38.08 % REE)

Hellandite-(Ce) Classification

Dana Class:

54.2.2.4 (54)Nesosilicate Borosilicates and Some Beryllosilicates

(54.2)with B in [4] coordination

(54.2.2)Hellandite group

54.2.2.1 Hellandite-(Y) (Ca,REE)4(Y,Ce)2(Al,[])2[Si4B4O22](OH)2 P 2/a 2/m

54.2.2.2 Tadzhikite-(Y)! Ca4(Y,Ce)2(Ti,Al,Fe,[])2[Si4B4O22](OH)2 P 2/a 2/m

54.2.2.3 Tadzhikite-(Ce) Ca4(Ce,Y)2(Ti,Al,Fe,[])2[Si4B4O22](OH)2 P 2/a 2/m

54.2.2.4 Hellandite-(Ce) ! (Ca3REE)4Ce2Al[]2[Si4B4O22](OH)2 P 2/a 2/m

54.2.2.5 Mottanaite-(Ce)! Ca4(Ce,Ca)2AlBe2[Si4B4O22]O2 P 2/a 2/m

54.2.2.6 Ciprianiite! Ca4[(Th,U)(REE)]2(Al,[])2[Si4B4O22](OH,F)2 P 2/a 2/m

Strunz Class:

VIII/F.36-15 VIII - Silicates

VIII/F - Inosilicates (chain and band) complex chain structure. Cylindric chains and others

VIII/F.36 - Caysichite-(Y) - Tadzhikite-(Ce) series

VIII/F.36-02 Grumantite NaHSi2O5·(H2O) F dd2 mm2

VIII/F.36-05 Caysichite-(Y) Y2(Ca,Gd)2Si4O10(CO3)3(H2O,O,OH)·3H20 Ccm21 mm2

VIII/F.36-10 Hellandite-(Y) (Ca,REE)4(Y,Ce)2(Al,[])2[Si4B4O22](OH)2 P 2/a 2/m

VIII/F.36-15 Hellandite-(Ce) (Ca3REE)4Ce2Al[]2[Si4B4O22](OH)2 P 2/a 2/m

VIII/F.36-20 Tadzhikite-(Ce) Ca4(Ce,Y)2(Ti,Al,Fe,[])2[Si4B4O22](OH)2 P 2/a 2/m

VIII/F.36-25 Tadzhikite-(Y)! Ca4(Y,Ce)2(Ti,Al,Fe,[])2[Si4B4O22](OH)2 P 2/a 2/m

VIII/F.36-30 Mottanaite-(Ce)! Ca4(Ce,Ca)2AlBe2[Si4B4O22]O2 P 2/a 2/m

VIII/F.36-40 Ciprianiite! Ca4[(Th,U)(REE)]2(Al,[])2[Si4B4O22](OH,F)2 P 2/a 2/m

VIII/F.36-60 Ashcroftine-(Y) K5Na5(Y,Ca)12Si28O70(OH)2(CO3)8·8(H2O) I 4/mmm 4/m 2/m 2/m

Other Hellandite-(Ce) Information

References:

NAME( AmMin, Vol 84, p 913) PHYS. PROP.(AmMin, Vol 84, p 913) OPTIC PROP.(AmMin, Vol 84, p 913)

See Also:

Links to other databases for Hellandite-(Ce) :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -MinDAT 6 -MinMax(Deutsch) 7 -MinMax(English) 8 -Mineralienatlas (Deutsch) 9 -QUT Mineral Atlas 10 - Uranium Minerals

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Hellandite-(Ce)

(Ca3REE)4Ce2Al[ ]2[Si4 B4O22](OH)2
Dana No: 54.2.2.4 Strunz No: VIII/F.36-15
Locality:

Notes: