Chevkinite-(Ce) Mineral Data

Chevkinite-(Ce) Mineral Data +

General Chevkinite-(Ce) Information

Chemical Formula:

(Ce,La,Ca,Th)4(Fe++,Mg)2(Ti,Fe+++)3Si4O22

Composition:

Molecular Weight = 1,205.27 gm

Calcium 2.66 % Ca 3.72 % CaO

Lanthanum 16.13 % La 18.92 % La₂O₃

Cerium 19.76 % Ce 23.15 % Ce₂O₃

Thorium 1.93 % Th 2.19 % ThO₂

Magnesium 0.40 % Mg 0.67 % MgO

Titanium 9.93 % Ti 16.57 % TiO₂

Iron 10.66 % Fe 10.73 % FeO / 3.31 % Fe₂O₃

Silicon 9.32 % Si 19.94 % SiO₂

Oxygen 29.20 % O

______ ______

100.00 % 99.20 % = TOTAL OXIDE

Empirical Formula:

Ce_1.7La_1.4Ca_0.8Th_0.1Fe²⁺_1.8Mg_0.2Ti_2.5Fe³⁺_0.5Si₄O₂₂

Environment:

Secondary mineral in titanium and cerium bearing rocks and as an accessory mineral in some granites.

IMA Status:

Valid Species (Pre-IMA) 1839

Locality:

Miask in the Ilmen Mountains, Russia. Link to MinDat.org Location Data.

Name Origin:

Named for General Konstatin Vladimirovich Tschevkin [Chevkin] (1802-1875), Chief o f Staff of the Russian Mining Engineers Corps.

Synonym:

Tscheffkinite

Chevkinite-(Ce) Image

Images:

Chevkinite-(Ce)

Comments: Dark brown crystal of chevkinite-(Ce).
Location: Miass, Central Ural Mountains, Russia. Scale: 3 cm.
© Dave Barthelmy

Chevkinite-(Ce) Crystallography

Axial Ratios:

a:b:c =2.3298:1:1.9261

Cell Dimensions:

a = 13.56, b = 5.82, c = 11.21, Z = 2; beta = 100.75° V = 869.16 Den(Calc)= 4.61

Crystal System:

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

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

By Intensity(I/I_o): 2.71(1), 3.14(1), 3.17(1),

Crystal Structure:

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Sokolova E V , Hawthorne F C , Della Ventura G , Kartashov P M , The Canadian Mineralogist , 42 (2004) p.1013-1025, Chevkinite-(Ce): Crystal structure and the effect of moderate radiation-induced, damage on site-occupancy refinement, Locality: Mongolia, Crystal (1)

View Additional jPOWD Structure files for Chevkinite-(Ce)
[1] [2] [3] [4]

Physical Properties of Chevkinite-(Ce)

Cleavage:

None

Color:

Brownish black, Dark red.

Density:

4.5

Diaphaniety:

Translucent to subtranslucent to opaque

Fracture:

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

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

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

Hardness:

5-5.5 - Apatite-Knife Blade

Luminescence:

Non-fluorescent.

Luster:

Earthy (Dull)

Streak:

black

Optical Properties of Chevkinite-(Ce)

Optical Data:

Biaxial (-), a=1.967-1.973, b=2.02, g=2.05, bire=0.0770-0.0830

Pleochroism (x):

nearly colorless.

Pleochroism (y):

pale reddish brown.

Pleochroism (z):

dark reddish brown.

Calculated Properties of Chevkinite-(Ce)

Electron Density:

r_electron=4.23 gm/cc
note: r_{Chevkinite-(Ce)}=4.61 gm/cc.

Fermion Index

Fermion Index = 0.02017
Boson Index = 0.97983

Photoelectric:

PE_{Chevkinite-(Ce)}= 225.16 barns/electron
U=PE_{Chevkinite-(Ce)} x r_electron= 951.81 barns/cc.

Radioactivity:

GRapi = 37,661.01 (Gamma Ray American Petroleum Institute Units)

Chevkinite-(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) 807.64 ±201.91 grams of pure Chevkinite-(Ce) .

**Estimated Radioactivity from Chevkinite-(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 / 7.45 cm	862,490	2.33E-05	37,661.01	12.38
100 gm / 3.46 cm	86,249	2.33E-06	3,766.10	1.24
10 gm / 1.61 cm	8,625	2.33E-07	376.61	0.12
1 gm / 7.45 mm	862	2.33E-08	37.66	0.01
0.1 gm / 3.46 mm	86	2.33E-09	3.77	0.00
0.01 gm / 1.61 mm	9	2.33E-10	0.38	0.00
0.001 gm / 0.75 mm	1	2.33E-11	0.04	0.00

Weight of pure Chevkinite-(Ce) in grams (gm) and Calculated Diameter of a Sphere with a Density of 4.61 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

Chevkinite-(Ce) Classification

Dana Class:

56.2.8.1 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.2)with cations in [4] and/or >[4] coordination

(56.2.8)Perierite - Chevkinite group

56.2.8.1 Chevkinite-(Ce) (Ce,La,Ca,Th)4(Fe,Mg)2(Ti,Fe)3Si4O22 C 2/m 2/m

56.2.8.2 Strontiochevkinite (Sr,REE)4Fe(Ti,Zr)2Ti2Si4O22 C 2/a 2/m

56.2.8.3 Perrierite-(Ce) (Ce,La,Ca)4(Fe,Mg)2(Ti,Fe)3Si4O22 C 21/a 2/m

56.2.8.4 Orthochevkinite* (Ce,La,Ca,Na,Th)4(Fe,Mg)2(Ti,Fe)3Si4O22 Unk Ortho

56.2.8.5 Rengeite! Sr4ZrTi4Si4O22 P 2₁/a 2/m

56.2.8.6 Matsubaraite! Sr4TiTi4Si4O22 P 2₁/a 2/m

56.2.8.7 Polyakovite-(Ce)! (Ce,La,Nd,Pr,Ca)4(Mg,Fe)(Cr,Fe)2(Ti,Nb)2Si4O22 C 2/m 2/m

56.2.8.8 IMA2003-017! (REE,Ca)4(Fe,Ti,Fe,[])(Ti,Fe,Fe,Nb)4Si4O22 C 2/m 2/m

Strunz Class:

VIII/C.07-210 VIII - Silicates

VIII/C - Sorosilicates with [Si2O7]6-, with anions unfamiliar to tetraheders [O,OH,F]

VIII/C.07 - Bertrandite - Strontiochevkinite series

VIII/C.07-10 Bertrandite Be4Si2O7(OH)2 Ccm21 mm2

VIII/C.07-210 Chevkinite-(Ce) (Ce,La,Ca,Th)4(Fe,Mg)2(Ti,Fe)3Si4O22 C 2/m 2/m

Other Chevkinite-(Ce) Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Chevkinite-(Ce)

(Ce,La,Ca,Th)4(Fe++,Mg)2(Ti,Fe+++)3Si4O22
Dana No: 56.2.8.1 Strunz No: VIII/C.07-210
Locality:

Notes: