The Mineralogy of Naujakasite.

Authors

  • Ole V. Petersen

Abstract

Naujakasite occurs as platy rhomb-shaped, silvery white crystals in the lujavrite at two localities Tuperssuatsiait and Kvanefj eld, in the Ilimaussaq 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 2½-3. Naujakasite is biaxial negative, with 2Vα between 52° and 71°, nα = 1.537, nβ = 1.551 - 1.549, nγ = 1.556, 2Vα calculated= 62°- 75°. Ʇ(001): y = + 45 °. X-ray diffraction yields: a0 = 15.039 Å, 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

1967-11-20

How to Cite

Petersen, O. V. (1967). The Mineralogy of Naujakasite. Meddelelser Om Grønland, 181(6), 21 pp. Retrieved from https://tidsskrift.dk/meddrgroenland/article/view/153072

Issue

Vol. 181 No. 6 (1967): Meddelelser om Grønland

Section

Artikler

License

Coypyright by the authors and the Commision for Scientific Research in Greenland. No parts of the publications may be reproduced in any form without the written permission by the copyright owners.