Chevkinite-(Ce)
Current inventory: 0 gems
 

  
Chevkinite-(Ce) was named in 1839 by Gustav Rose in honor of General-Major Konstantin Vladimirovich Tschevkin [Chevkin] (1802-1875), Chief of Staff of the Russian Mining Engineers Corps; and its Cerium (Ce) content.

Discovered in 1839; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

(Ce,La,Ca,Th)₄(Fe²⁺,Mg)(Fe²⁺,Ti,Fe³⁺)₂(Ti,Fe³⁺)₂(Si₂O₇)₂O₈

Cerium Lanthanum Calcium Thorium Iron Magnesium Titanium Silicate

Molecular Weight:

1,205.27 gm

Composition:

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

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/C.17-20

Nickel-Strunz 10th Ed. ID:

9.BE.70

9 : SILICATES (Germanates)
B : Sorosilicates
E : Si₂O₇ groups, with additional anions; cations in octahedral [6] and greater coordination

Related to:

Chevkinite Group. Dimorphous with Perrierite.

Members of Group:

Chevkinite Group: Chevkinite-(Ce), Christofschäferite-(Ce), Dingdaohengite-(Ce), Hezuolinite, Maoniupingite-(Ce), Matsubaraite, Perrierite-(Ce), Perrierite-(La), Polyakovite-(Ce), Rengeite, Strontiochevkinite, Strontium Perrierite 

Varieties:

Niobochevkinite

Synonyms:

Tscheffkinite-(Ce)

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Small lamellar, lenticular, and prismatic crystals; massive, in lumps to 10 cm.

Twinning:

Twin plane {001}

Physical Properties

Cleavage:

None

Fracture:

Irregular/uneven to Conchoidal

Tenacity:

Brittle

Moh's Hardness:

5.5 - 6.0

Density:

4.53 - 4.67 (g/cm³)

Luminescence:

None

Radioactivity:

Weak; GRapi = 37,661.04 (Gamma Ray American Petroleum Institute Units)

Health Warning:

Contains thorium - always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest. Avoid prolonged exposure in proximity of the body. Store away from inhabited areas.

Optical Properties

Color:

Dark reddish brown to black; red to orange-brown inner reflections

Transparency:

Opaque except on thin edges

Luster:

Resinous to dull

Refractive Index:

1.967 - 2.050  Biaxial ( - )

Birefringence:

0.077 - 0.083

Dispersion:

Distinct to strong; r < v

Pleochroism:

X = almost colorless; Y = reddish brown; Z = dark brown

Occurances

Geological Setting:

As an accessory mineral in some granites, and in pegmatites associated with alkalic granite and syenites; in air-fall ash deposits.

Common Associations:

Titanite, Monazite, Apatite, Cronstedtite, Quartz (Aquarius Mountains, Arizona, USA).

Common Impurities:

Ca, Nb, Mg, Th, Sr, Zr

Type Locality:

Pit No. 17, Ilmen Natural Reserve, Ilmen Mts, Chelyabinsk Oblast', Southern Urals, Urals Region, Russia

Year Discovered:

1839

View mineral photos:

Chevkinite-(Ce) Mineral Photos and Locations

Unusual Gem Categories

Black Gems, Radioactive Gems, Rare Earth Elements (REE) Gems

More Information

Mindat.org
Webmineral.com

Chevkinite-(Ce) is a rare REE (Rare Earth Element) titano-silicate mineral that is weakly radioactive due to its almost 2% thorium (Th) content. Chevnikite-(Ce) contains the rare earth elements cerium (Ce) and Lanthanum (La). It is found as opaque, dark reddish brown to black prismatic crystals with resinous to sub-metallic luster and Moh's hardness of 5.5-6.0.

Chevkinite-(Ce) was discovered in 1839 at the Pit No. 17, Ilmen Natural Reserve, Ilmen Mts, Chelyabinsk Oblast', Southern Urals, Urals Region, Russia. It was named by Gustav Rose in honor of General-Major Konstantin Vladimirovich Tschevkin [Chevkin] (1802-1875), Chief of Staff of the Russian Mining Engineers Corps; and its Cerium (Ce) content.

Chevkinite-(Ce) distribution: from the Ilmen Mountains, Southern Ural Mountains; the Keivy massif, Kola Peninsula; and elsewhere in Russia. At Buer, Björkedalen, Norway. From Glen Bay, Na h-Eagan, and Conachair, in the Isles of St. Kilda, Outer Hebrides, Scotland. In Madagascar, from the Tordendrika-Ifasina region, Androngovato, and Ifasina, Ambatofinandrahana. From the Chilas area, near Nanga Parbat, Pakistan. In the USA, in the Aquarius Mountains, Mohave County, Arizona; the Jemez Mountains and Pueblo Mesa, Rio Arriba County, New Mexico; at Onion Creek, Grand County, Utah; in Yellowstone National Park, Wyoming; from Irish Flats, Meade County, Kansas. Also in the Spruce Pine district, Mitchell County, North Carolina; near Martin's Store, Nelson County, Virginia; and in New Hampshire, from near Stark, Coos County. A few other localities have been verified.
 

  
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