Nyerereite - Na2Ca(CO3)2

Nyerereite is a very rare sodium calcium carbonate mineral with formula Na2Ca(CO3)2. It forms colorless, platey pseudohexagonal orthorhombic crystals that are typically twinned. Nyerereite is not stable in contact with the atmosphere and rapidly breaks down.

It was first recognized and described by J.B. Dawson from the Ol Doinyo Lengai carbonatite lavas in 1963 and named in honor of the president of Tanzania, Julius Nyerere. In the carbonatite lava it is associated with the potassium bearing gregoryite. It has also been reported from the Afrikanda alkaline intrusive complex, in the Kola Peninsula, Russia. Since nyerereite is very unstable when it reaches the surface it creates pseudomorphs. when it cools down and gets hydrated nyerereite transform in pirssonite that has a chemical formula of Na2Ca(CO3)2*2(H2O).

Optical Properties:
• Relief: low
• Color: colorless
• Habit: Tabular crystals, platey pseudohexagonal
• Interference colors: I order gray-yellow


Bibliography



• D. B. Clarke (1995): Cordierite in felsic igneous rocks; a synthesis Mineralogical Magazine. • Deer, W.A., Howie, R.A., Zussman, J. (1998) Rock-forming Minerals.
• Optical Mineralogy : The Nonopaque Minerals by Phillips / Griffen
• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc


Photo
oldoynio(46).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
oldoynio.jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. XPL image , 10x (Field of view = 2mm)
lengai2013fg(29).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
leeengai(5).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. PPL image , 10x (Field of view = 2mm)
leeengai(6).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
leeengai(7).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
leeengai(41).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
leeengai(42).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
leeengai(43).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
leeengai(38).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. XPL image , 10x (Field of view = 2mm)
leeengai(39).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. XPL image , 10x (Field of view = 2mm)
leeengai(40).jpg

Tabular crystals of Nyerereite (altered) in a Natrocarbonatite from Ol Doinyo Lengai. XPL image , 10x (Field of view = 2mm)
leeengai(19).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. PPL image , 10x (Field of view = 2mm)
leeengai(20).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. PPL image , 10x (Field of view = 2mm)
leeengai(21).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. XPL image , 10x (Field of view = 2mm)
lengai2013fg(35).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
lengai2013fg(36).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
lengai2013fg(19).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
lengai2013fg(20).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)
lengai2013fg(21).jpg

Tabular crystals of Nyerereite in a Natrocarbonatite from Ol Doinyo Lengai. The rounded crystals are Gregorite. XPL image , 10x (Field of view = 2mm)