Hellandite-(Y)

 IMA-2000 F
Uranium     (trace)
Thorium     (trace)		 54.2.2.1
(Dana Classification Number)
(No Images) 8.F/36.10
(Strunz ID)

Property Data Remarks
Named for: Amund Theodor Helland (1846-1918), geologist, Oslo, Norway
Alternate
    Name(s):
  • Hellandite
    		•   
    Mineral Class:
    Silicates
      Inosilicates - complex chain structure.
    Cylindric chains and others
        Caysichite-(Y) - Tadzhikite-(Ce) series
    		 
    Chemical
        Formula:    		 (Ca,REE)4(Y,Ce)2(Al,[ ])2[Si4B4O22](OH)2  
    Chemical
        Composition:
    Aluminum: (Al) 1.97%
    Boron: (B) 4.20%
    Calcium: (Ca) 11.68%
    Cerium: (Ce) 6.81%
    Hydrogen: (H) 0.20%
    Oxygen: (O) 37.30%
    Silicon: (Si) 10.91%
    Yttrium: (Y) 12.95%
    Thorium: (Th) (Trace)
    Uranium: (U) (Trace)
    REE2O3
        Lanthanum
        Neodymium
        Praeseodymium
        Samarium    		  
    (La)
    (Nd)
    (Pr)
    (Sm)    		 | 
    |
    |
    |
    |    		 13.99%
    		by weight
    Molecular
        Weight:    		 1,029.47 daltons (amu)
    Specific
        Radioactivity:

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

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    467 1.26 × 10-08 0.01 .69

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Monoclinic - Prismatic
    Axial Ratios: a: 4.0275
    b: 1
    c: 2.1845
    Cell Dimensions: a: 18.99 Å
    b: 4.715 Å
    c: 10.3 Å
    Z: 2
    b: 111.4°
    V: 858.66 Å3
    DenCalc: 3.98
    H-M Symbol: 2/m
    Space Group: P2/a
    X-Ray Diffraction:
      By Intensity ( I/Io )    		 (1): 2.63 Å
    (0.6): 1.89 Å
    (0.6): 2.82 Å
    		 
    Habit:
  • Prismatic
    		•   
    Cleavage:
    [001] Poor
    [010]  
    [100] Poor
    		 
    Fracture: Brittle - Conchoidal  
    Moh's
        Hardness:    		 5.5 - 6  
    Density: 3.7 grams/cm3
    Color: Yellow, Green yellow, Green, Reddish yellow, Grey-green, Grayish black, Reddish brown, Black  
    Streak:    
    Luster: Vitreous - Greasy  
    Diaphaneity: Translucent to Subtranslucent  
    Pleochroism:
    (x):  
    (y:)  
    (z:)  
    		 
    Ultra Violet
        Fluorescence:    		 Non-Fluorescent  
    Magnetism: Non-magnetic  
    Occurance:
  • Pegmatite
    		•   
    Associated
        Minerals:

    Albite, Allanite-(Ce), Almandine, Biotite, Calcite, Chalcopyrite, 'Chlorite Group', Epidote, Gadolinite-(Y), Goethite, Gypsum, Hingganite-(Y), Kainosite-(Y), Magnetite, Microcline, Muscovite, Pyrite, Pyrrhotite, Quartz, Scheelite, Spessartine, Talc, Titanite, Zircon

    Mineral   -   > 67% of sites
    Mineral   -   > 44% of sites
    Mineral   -   > 33% of sites
    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Hellandite-(Y)
    Localities:

    Rare

    (Hellandite-(Y) Localities)
    Notes:

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

    Crystals are probably metamic.