ZEMKORITE, A NEW CARBONATE FROM KIMBERLITES OF YAKUTIA

Abstract

In the Udachnaya kimberlite pipe in the Daldyn field, Yakutia, the authors discovered and studied in our Institute the new carbonate Na2Ca(CO3)2, called zemkorite and close in composition to the known carbonate nyerereite, but differing from it in structure. Zemkorite was found at a depth of 400 to 450 m in the east kimberlite body of the twin Udachnaya pipe. The kimberlite containing this mineral is completely unserpentinized and has been described as the analog of unaltered kimberlite. Shortite and more rarely halite are often observed together with zemkorite. The new mineral usually fills fine fractures in the rock, is developed along the contact of small xenoliths and phenocrysts with the rock matrix and, very rarely, forms fan-shaped aggregates 3 to 4 mm in size. Zemkorite is a colorless, water-clear mineral with glassy to pearly luster. It is brittle. No crystal faces were found. Additional aspects of the subject are discussed.