05-24. Iolite – cordierite #4

From a resource by T. Armbruster, study of an iolite crystal.


05-23. Iolite – cordierite #3

Iolite unit cell, atomic arrangement & connection. It looks like an astronomer’s sky or planetary map. The very small and the very large are not that different. Background: tessellation of the same iolite unit polyhedral structure.

From a resource by Armbruster, single-crystal study from Ruby Island, New Zealand.


05-21. Iolite – cordierite #1.

Iolite – or cordierite as the mineral is also called, is week #21 theme of this 52-week tour of the geometry of nature. The iolite crystal has an amazingly harmonious and well organized – antic tessellation – look and structure.

The name “iolite” comes from the Greek word for violet. The crystal comes in blue, bluish violet; greenish, gray to very pale blue in thin section. It is also called “water-sapphire” or “Vikings’ Compass” because Leif Eriksson and other Viking explorers used it to determine the direction of the sun on overcast days. It may qualify as the world’s first polarizing filter.

Its structure belongs to the dipyramidal, orthorhombic family.

The largest iolite deposits today can be found in Madagascar, Myanmar, Sri Lanka, India, and Brazil.



05-18. Tourmaline – elbaite #5.

The dance of the Elbaite. Sometimes it takes more effort to put less than to put more! The harmony of the atom and polyhedra arrangement is so pleasant to look at, it just was worth letting it be just – as is.

From a resource by Ertl, Tillmanns, Ntaflos, Francis, Gieste, Korne, Hughes, Lengauer and Prem. Study of an elbaite from  Manjaka, Sahatany Valley, Madagascar.