The mineralogy of naujakasite

Authors

  • O.V Petersen
  • E.I Semenov
  • M.E Kazakova
  • V.J Bukin
  • H Sørensen
  • Z.T Katajeva

DOI:

https://doi.org/10.34194/bullggu.v75.6615

Abstract

Naujakasite occurs as platy rhomb-shaped, silvery white crystals in the lujavrite at two localities Tuperssuatsiait and Kvanefjeld, in the Ilímaussaq alkaline intrusion, South Greenland. Occasionally naujakasite constitutes about three quarters of the rock. The crystals are monoclinic with three distinct cleavages; {001} mica-like, {010} and {401} distinct but somewhat irregular. (001): (401) = 93°. The density is 2.262 g/cm3, the hardness 2 1/2-3.

Naujakasite is biaxial negative, with 2Vα between 52° and 71°, nα = 1.537, nβ = 1.551-1.549, nγ = 1.556, 2Vaα calculated = 62°-75°. Ʇ 1(001): γ = +45°.

X-ray diffraction yields: a0 = 15.039 A, b0 = 7.991 Å, C0 = 10.487 Å and β = 113.67°. Vol. 1154 Å3. Space groups C 2/m, Cm or C2.

The formula (Na, K)6 (FeII, Mn, Ca) (Al, FeIII)4 Si8O26 · H2O, Z = 2 is proposed for the naujakasite although there are some differences between observed and theoretical values.

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Published

1968-11-20

How to Cite

Petersen, O., Semenov, E., Kazakova, M., Bukin, V., Sørensen, H., & Katajeva, Z. (1968). The mineralogy of naujakasite. Bulletin Grønlands Geologiske Undersøgelse, 75, 2–21. https://doi.org/10.34194/bullggu.v75.6615

Issue

Vol. 75 (1968): Contribution to the mineralogy of Ilímaussaq, Nos 9–11

Section

Article

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This article is distributed under a CC-BY 4.0 licence, permitting free redistribution and reproduction for any purpose, even commercial, provided proper citation of the original work. Author(s) retain copyright over the article contents.