• Sodalite means sodium stone and it was given this name by
Thomson in 1811.
• It has a cubic crystal structure with the space group P43n.
• The structure (pictured below) is characterized by the
combination of silicon and aluminum atoms connected by
oxygen bridges in cage-like frameworks, which in turn are
packed to give a cubic structure.
2Presented by: Raja Wajahat
• This framework has the composition Na6Al6Si6O24, but
contains additional ions next to the cations in the enclosed
• Thus, the average stoichiometry of sodalite is increased by two
moles of Na+ and Cl– to Na8Al6Si6O24Cl2.
3Presented by: Raja Wajahat
• Lasurit, also called lapis lazuli, is a close relative of sodalite
that was highly valued by the early civilizations of the Near
East and in Egypt.
• In its sodalite cage, it contains radical anions of sulfur, which
are regarded as the cause of the intense blue color
(ultramarine) of the mineral.
4Presented by: Raja Wajahat
• Various reasons have been suggested for the origin of the color
• suggestions include the formation of colloidal sodium in the
cages and the presence of radical anions such as SO3–, Cl2–,
• That the color is due to a metastable state, seems obvious, as
the color disappears on heating.
6Presented by: Raja Wajahat
• Sodalite often occurs in igneous rocks with rather low
SiO2 content, but also in metasomatized calcareous rocks, e.g.,
• Worldwide, more than three hundred natural sources of
sodalite are known, it is usually found as granular to massive
aggregates of more than one meter and rarely as well-formed
7Presented by: Raja Wajahat
• Sodalite is used as a gemstone or for the manufacture of
• In places, such as in Bahia, Brazil, where sodalite is more
abundant, tiles and claddings are also made from it.
8Presented by: Raja Wajahat