Occurs in a cavity in a late-stage hydrothermal albitite vein in the Ilímaussaq alkaline complex. (Eudialyte group, predominance of Sr in N(4) and Nb in M(3); structure determined).
IMA Status:
Approved IMA 2002 (Dana # Added)
Locality:
Ilímaussaq alkaline complex, South Greenland. Link to MinDat.org Location Data.
Name Origin:
Named for the northern part of the complex, at theTaseq slope.
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Petersen O V , Johnsen O , Gault R A , Niedermayr G , Grice J D , Neues Jahrbuch fur Mineralogie, Monatshefte , 2004 (2004) p.83-96, Taseqite, a new member of the eudialyte group from the Ilímaussaq alkaline complex, South Greenland, Locality: Ilimaussaq alkaline complex, South Greenland, Note: water and OHs located at O20 and O21
Physical Properties of Taseqite
Cleavage:
{001} Fair
Color:
Clove brown, Yellowish brown, Lemon yellow.
Density:
3.24
Diaphaneity:
Transparent
Fracture:
Brittle - Uneven - Very brittle fracture producing uneven fragments.
Habit:
Platy - Sheet forms (e.g. micas).
Luster:
Vitreous (Glassy)
Streak:
light brownish white
Optical Properties of Taseqite
Gladstone-Dale:
CI meas= 0.02 (Excellent) - where the CI = (1-KPDmeas/KC) CI calc= 0.007 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2011,KPDmeas= 0.1986,KC= 0.2026 Ncalc = 1.65 - 1.66
Optical Data:
Uniaxial (-), e=1.6378, w=1.6494, bire=0.0116.
Calculated Properties of Taseqite
Electron Density:
Bulk Density (Electron Density)=3.08 gm/cc note: Specific Gravity of Taseqite =3.20 gm/cc.
Fermion Index:
Fermion Index = 0.02 Boson Index = 0.98
Photoelectric:
PETaseqite = 37.74 barns/electron U=PETaseqite x relectron= 116.08 barns/cc.
Radioactivity:
GRapi = 87.15 (Gamma Ray American Petroleum Institute Units)
Concentration of Taseqite per GRapi unit = 1.15 (%)
Estimated Radioactivity from Taseqite - barely detectable