Britholite-(Ce)

 IMA-1987
Thorium 52.4.9.1
(Dana Classification Number)
(Images) 8/B.27-60
(Strunz ID)

Property Data Remarks
Named for: the Greek word for weight, in allusion to its density, and its Cerium content
Alternate
    Name(s):
  • Beckelite
  • Lessingite-(Ce)
  • Pravdite
    		•   
    Mineral Class:
    Silicates
      Nesosubsilicates, with anions unfamiliar to tetraheders, with groups [SO4]2-, [CrO4]2- and [PO4]3-
        Fluorellestadite - Lessingite-(Ce) series
    		 
    Chemical
        Formula:    		 (Ce,Ca,Th,La,Nd)5(SiO4,PO4)3(OH,F)  
    Chemical
        Composition:
    Calcium: (Ca) 14.71%
    Cerium: (Ce) 16.53%
    Fluorine: (F) 0.50%
    Hydrogen: (H) 0.11%
    Lanthanum: (La) 7.29%
    Neodymium: (Nd) 3.78%
    Oxygen: (O) 26.85%
    Phosphorus: (P) 2.03%
    Silicon: (Si) 9.94%
    Thorium: (Th) 18.25%
    		by weight
    Molecular
        Weight:    		 762.67 daltons (amu)
    Specific
        Radioactivity:

    (All radiation is for a 1 gram, fully aged specimen)

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    8.178 × 1003 2.21 × 10-07 0.12 11.66

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System:   Hexagonal - Dipyramidal Monoclinic
    Axial Ratios: a: 1  
    b:    
    c: 0.73001  
    Cell Dimensions: a: 9.63 Å 9.58
    b:   9.59 Å
    c: 7.03 Å 6.98
    Z: 2 2
    b:   89.70°
    V: 564.60 Å3  
    DenCalc: 4.49  
    H-M Symbol:   6/m  
    Space Group:   P63/m P21
    X-Ray Diffraction:
      By Intensity     		( I/Io ) (1): 2.836 Å (1): 2.84 Å
    (0.8): 3.48 Å (1): 2.84 Å
    (0.8): 2.809 Å (0.8): 3.48 Å
    (0.5): 1.858 Å (0.6): 3.11 Å
    (0.4): 3.211 Å (0.6): 4.1 Å
    (0.4): 3.927 Å    
    (0.4): 4.116 Å    
    		Hexagonal data per Dave Barthelmy

    Monoclinic data per
    Minerals and their Localities,
    J.H. Bernard and
    J. Hyrsl
    Habit:
  • Pseudo Hexagonal
  • Prismatic
    		•   
    Cleavage: None  
    Fracture: Brittle - Conchoidal  
    Moh's
        Hardness:    		 5 - 5.5  
    Density: 4.2 - 4.7 grams/cm3
    Color: Brown, Greenish brown, Yellow, Resin brown, Black  
    Streak:    
    Luster: Adamantine - Resinous  
    Diaphaneity: Sub-opaque  
    Dichroism:
    (e:) Colorless
    (w:) Brown
    		 
    Ultra Violet
        Fluorescence:
    Long Wave:  
    Short Wave:  
    		 
    Magnetism: Non-magnetic  
    Occurance:
  • In nepheline syenites, pegmatites and contact deposits related to them
  • within volcanically deposited minerals on Monte Somma and Vesuvius
    		•   
    Associated
        Minerals:

    Aegirine, Albite, Allanite-(Ce), Analcime, Andradite, Augite, Baddeleyite, Barite, Bastnäsite-(Ce), Biotite, Böhmite, Calcite, Cancrinite, Chalcopyrite, Diopside, Epididymite, Epidote, Eudialyte, Eudidymite, Fluorapatite, Fluorapophyllite, Fluorite, Galena, Gibbsite, Gonnardite, Hambergite, Helvite, Hematite, Ilmenite, Magnetite, Meliphanite, Microcline, Molybdenite, Monazite-(Ce), Natrolite, Nepheline, Opal, Parisite-(Ce), Pectolite, Phlogopite, Pyrite, Pyrochlore, Quartz, Riebeckite, Rutile, Sodalite, Sphalerite, Thomsonite, Thorite, Titanite, Zircon

    Mineral   -   > 59% of sites
    Mineral   -   > 44% of sites
    Mineral   -   > 26% of sites
    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Britholite-(Ce)
    Localities:

    Rare

    Britholite-(Ce) Localities
    Notes:

    Strongly radioactive a- and b-particles, g-rays.

    Britholite-(Y), its sister mineral (Dana 52.4.9.2), is not radioactive.

    Crystals are probably metamic.

    Britholite-(Ce) Images

    Specimen #1
    (001a) (001b) (001c) (001d)

     
    Rusty Gold Mine, Jamestown District, Boulder Co., Colorado, U.S.A.

    Specimen Notes

    Occurrence - The Britholite-(Ce) occurs on a matrix of fine grained white quartz. The associated minerals occurring with it are: Rose Quartz; Goethite; Garnet; Muscovite and Biotite micas; Uraninite (believed to be petrified wood); Thorite; and several others.

    Crystals - The crystals appear to be hexagonal prisms with poorly defined terminations. In general, the generic Hexagonal - Dipyramidal form, only greatly elongated, and the termination more angular.

    While some crystals occur singularly, as in image (001d), the usual occurrance is for Britholite-(Ce) crystals to occur closely statcked together in parallel masses. This can give it the appearance of parallel plates due to the well defined prismatic faces and sharp edges of its crystals.

    A few of the Britholite-(Ce) are distorted into appearing as trapezoidal in cross section. These are crystals that are all solitary and well away from the masses of other Britholite-(Ce) crystals. These may be the monoclinic crystals mentioned in Minerals and their Localities by J.H. Bernard and J. Hyrsl.

    Appearence -  

    Diaphaniety - The Britholite-(Ce) crystals all appear to be opaque, with no transmission of light.

    Luster - The surfaces of the crystals are all highly textured and rough, but with sharp prismatic edges. Its luster is adamantine, but can seem almost earthy in areas due to the texturing.

    Freshly broken surfaces appear adamantine in luster.

    Cleavage - Though no cleavage is known for Britholite-(Ce), it does have a preference toward breaking with the {001} plane, across the length of the crystal.

    Specimen Physical Properties
    Size 1.65 cm 1.52 cm 1.27 cm
    Weight: 6.23 grams    
    g-Radiation Level: 22 cmp 0.022 msieverts background: 18 cpm