Kreiterite

kreiterite

aegirine

pectolite

sokolovaite

Images

Formula: CsLi2Fe3+Si4O10F2
Phyllosilicate (sheet silicate), trioctahedral mica group of the mica group, cesium- lithium- and fluorine- bearing mineral
Crystal System: Monoclinic
Specific gravity: 3.33 measured, 3.342 calculated
Hardness: 2½
Streak: White
Colour: Colourless
Luminescence: Luminesces pale yellow under short wave UV
Environments

Pegmatites
Carbonatites
Metamorphic environments

Kreiterite is a new mineral, approved in 2019 and to date (February 2025) reported only from the type locality.

Localities

At the type locality, the Dara-i-Pioz Massif, Districts of Republican Subordination, Tajikistan, outcrops of the massif are extremely inaccessible and most mineralogical research is done on material collected from the associated glacial moraine. The central part of the massif is composed of aegirine syenites and fenites. The outer rim is composed of binary (containing both muscovite and biotite) tourmaline granite. In the eastern part of the massif there is a stock of coarse-grained cancrinite foyaite.

There is rich and diverse rare metal mineralisation associated with the widespread alkaline pegmatites, fenites and carbonatites of the massif. One of the characteristic features is the variety of the mica group minerals muscovite, annite, polylithionite, sokolovaite, orlovite, garmite, gorbunovite and kreiterite.

Another characteristic feature of the massif is cesium mineralisation. There are about 30 approved cesium minerals worldwide, of which at least 13 occur at the Dara-i-Pioz Massif: kupletskite-(Cs), telyushenkoite, zeravshanite, senkevichite, kirchhoffite, mendeleevite-(Ce), odigitriaite, mendeleevite-(Nd), fluorapophyllite-(Cs), the four cesium-dominant members of the mica group: sokolovaite, garmite, gorbunovite and kreiterite, and, in addition, there are three more cesium-bearing minerals from this association: yusupovite, letnikovite-(Ce) and kalyuzhnyite-(Ce). As with the other cesium micas occurring here, kreiterite was found in fragments of lumps (up to 2 m in size) of a rock composed mainly of granular quartz. Kreiterite occurs in polymineralic quartz-pectolite aggregates (from 1 to 15 cm in the largest dimension), sometimes embedded in this rock. These aggregates consist of manganese-bearing pectolite, quartz, strontium-bearing fluorite, aegirine, polylithionite, datolite and minor rare minerals. Kreiterite is very rare and is distributed unevenly in the quartz-pectolite aggregate. Most commonly, kreiterite aggregations are confined to the boundaries of aegirine with quartz, or, rarely, pectolite. Kreiterite occurs as fan-shaped clusters of lamellar grains and as small accretions in aegirine crystals.

Kreiterite is colourless in individual crystals and white in aggregates. It has a white streak and is visually indistinguishable from other light micas. The lustre is vitreous to pearly, cleavage is perfect and the flakes are flexible (CJMP 63.1.103-110).

Back to Minerals