Nyerereite

Photomicrograph of a thin section of natrocarbonatite lava. Nyerereite occurs as the central, rectangular crystals and also the long acicular crystals in the groundmass. The rounded colorless crystals are gregoryite and the opaques are alabandite. Fresh hot lava collected by Charles Milton.

© Tony Peterson

Photomicrograph of a thin section of natrocarbonatite lava (crossed polars). Nyerereite occurs as the central, rectangular crystals and also the long acicular crystals in the groundmass. The rounded crystals are gregoryite. Fresh hot lava collected by Charles Milton.

© Tony Peterson

A high-magnification (crossed polars) photomicrograph of an ultrathin (ca. 2 microns), doubly polished thin section of natrocarbonatite, showing details of the groundmass. Rectangular: nyerereite; rounded: gregoryite. The fingerprint-like patches are fine eutectric intergrowths of gregoryite (white) and mixed alkali halides (isotropic, black), ...

© Tony Peterson

Photomicrograph of a thin section of natrocarbonatite lava (crossed polars). Nyerereite occurs as the central, twinned crystals (here sectioned parallel to the basal plane) and also the long acicular crystals in the groundmass. The rounded crystals are gregoryite. Fresh hot lava collected by Charles Milton.

© Tony Peterson

Acicular crystals of nyerereite lining a vesicle in unaltered natrocarbonatite lava. The vesicle is exposed on a freshly broken surface. Acicular microphenocrysts of nyerereite comprise a large fraction of the groundmass of this lava specimen; some can be seen in this view as grey needles within the material around the vesicle. The black mineral ...

© Tony Peterson

FOV=1.5 mm. Acicular microphenocrysts of nyerereite in natrocarbonatite lava; the larger, rounded crystals are gregoryite. I include this slightly redundant photo as it clearly shows the form of the nyerereite crystals. The black mineral is alabandite. Blue is stained epoxy. Collection and photo, T. Peterson. Additional thin section photographs ...

© Tony Peterson

FOV=1.5 mm. Acicular crystals of nyerereite lining a vesicle in unaltered natrocarbonatite lava. The vesicle is exposed on a freshly broken surface. Acicular microphenocrysts of nyerereite comprise a large fraction of the groundmass of this lava specimen. The black mineral is alabandite. Collection and photo, T. Peterson. Thin section ...

© Tony Peterson

FOV=1.5 mm. Acicular crystals of nyerereite lining a vesicle in unaltered natrocarbonatite lava. The vesicle is exposed on a freshly broken surface. Acicular microphenocrysts of nyerereite comprise a large fraction of the groundmass of this lava specimen; some can be seen in this view as grey needles within the material around the vesicle. The ...

© Tony Peterson

Sony Alpha 7R ii, bellows, Mitutoyo M Plan 20x, aperture, Raynox DCR-250 retro, Stack-Master linear actor, stack shot control. Collection and photo: Stephan Wolfsried

© Stephan Wolfsried 10/2016

Colorless, bladed crystals of nyerereite on white anhydrite. Former Jaroslav Hyrsl collection. Rolf Luetcke specimen and photo.

Colourless Nyerereite crystals on unidentified creamy white matrix Ex Chris Deroo collection Acquired from Rik Dillen at the monthly MKA meeting on 11 March 2022

Colorless, bladed crystals of nyerereite on white anhydrite. Former Jaroslav Hyrsl collection. Rolf Luetcke specimen and photo.