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Townendite

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Formula:
Na8ZrSi6O18
Colour:
colorless
Lustre:
Vitreous
Hardness:
5 - 6
Specific Gravity:
2.95 (Calculated)
Crystal System:
Trigonal
Name:
Named for Roger Townend (b. 1938), a consulting mineralogist based in Perth, western Australia, for his contributions to mineralogy, particularly related to the Ilímaussaq deposit, southern Greenland.
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Classification of TownenditeHide

Approved
Approval Year:
2009

Pronounciation of TownenditeHide

Pronounciation:
PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Physical Properties of TownenditeHide

Vitreous
Transparency:
Transparent
Colour:
colorless
Streak:
white
Hardness:
5 - 6 on Mohs scale
Cleavage:
None Observed
Parting:
none
Fracture:
Conchoidal
Density:
2.95 g/cm3 (Calculated)

Optical Data of TownenditeHide

Type:
Uniaxial (-)
RI values:
nω = 1.563() nε = 1.555(3)
Max Birefringence:
δ = 0.008
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Low

Chemical Properties of TownenditeHide

Formula:
Na8ZrSi6O18
IMA Formula:
Na8ZrSi6O18

Crystallography of TownenditeHide

Crystal System:
Trigonal
Class (H-M):
3m (3 2/m) - Hexagonal Scalenohedral
Space Group:
R3m
Setting:
R3m
Cell Parameters:
a = 10.345(2) Å, c = 13.103(2) Å
Ratio:
a:c = 1 : 1.267
Unit Cell V:
1,214.40 ų (Calculated from Unit Cell)
Z:
3

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
5.286 (33)
5.175 (28)
4.240 (14)
3.698 (100)
3.280 (42)
2.645 (42)
2.585 (45)
1.849 (35)

Type Occurrence of TownenditeHide

General Appearance of Type Material:
small anhedral to subhedral grains with sizes of typically 10 to 50 µm, up to a maximum dimension of 100 µm.
Place of Conservation of Type Material:
Museum Victoria (GPO Box 666E, Melbourne, Victoria 3001, Australia), specimen number M51188.
Geological Setting of Type Material:
Lujavrite layer of the layered igneous intrusion. Possibly formed as an alteration product of steenstrupine-(Ce).
Associated Minerals at Type Locality:

Synonyms of TownenditeHide

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for TownenditeHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Grey, I.E., Macrae, C.M., Mumme, W.G. and Pring, A. (2010): Townendite, Na8ZrSi6O18, a new uranium-bearing lovozerite group mineral from the Ilímaussaq alkaline complex, Southern Greenland. American Mineralogist 95, 646-650.

Internet Links for TownenditeHide

Localities for TownenditeHide

ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Denmark (TL)
 
  • Greenland
    • Kujalleq
      • Narsaq
        • Ilímaussaq complex
          • Kuannersuit Plateau (Kvanefjeld)
Grey, I.E., Macrae, C.M., Mumme, W.G. and Pring, A. (2010): Townendite, Na8ZrSi6O18, a new uranium-bearing lovozerite group mineral from the Ilímaussaq alkaline complex, Southern Greenland. American Mineralogist 95, 646-650.
Mineral and/or Locality  
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