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.
05-20. Tourmaline – elbaite #7.
From a resource by Nuber & Schmetzer. An elbaite from Zambia.
05-19. Tourmaline – elbaite #6.
From a resource by Diego-Gatta, Danisi, Adamo, Meven and Diella.
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.
05-17. Tourmaline – elbaite #4.
There is something unique about the tourmaline-elbaite structure that keeps leading me to light, airy design. I can’t quite explain why – but I enjoy it!
From a resource by Vereshchagin, Rozhdestvenskaya, Frank-Kamenetskaya, Zolotarev, Mashkovtsev. Tourmaline-elbaite sample from Paraiba, Brazil.
05-16. Tourmaline – elbaite #3.
3187 atoms, 4936 bonds, 928 polyhedra went into this amazingly complex background structure. 43 atoms, 46 bonds, 8 polyhedra are on the central object. Interesting idea for an outdoor sculpture project!
From a resource by Erti, Hughes, Prowatke, Ludwig, Prasad, Brandstatter, Korner, Schuster, Pertlik, and Marschall – study of an elbaite structure from Anjanabonoina, Madagascar
05-15. Tourmaline – elbaite #2.
The essence of a tourmaline-elbaite crystal from Anjanabonoina, Madagascar. I left it almost as is – a minimal and dynamic symbol for what must have been a beautiful mineral.
From a resource by Ertl, Hughes, Prowatke, Ludwig, Prasad, Brandstatter, Korner, Schuster, Pertlik and Marschall.
05-14. Tourmaline – Elbaite #1.
Week 2 of this short exploration of the tourmaline geometry. The Elbaite has a similar geometry structure than the Dravite but its chemical composition is different. It should make for interesting compositions in terms of color and density of shapes.
Elbaite comes in virtually every color of the spectrum and has unique optical properties. Many green and blue specimens are strongly pleochroic. When viewed through their vertical axis, they appear darker in color than when seen through their horizontal axis. Certain Elbaites exhibit a cat’s eye effect when polished.
Brazil, Afghanistan, Italy are some of the countries where some of the most beautiful minerals were found.
Dutch traders brought tourmaline to Europe in the 1700s. They gave it the name, Aschentrekker, or “ash puller,” because they used the crystals to pull ashes from their Meerschaum pipes. This ability to gain magnetic powers and become electrically “polar” by means of heat distinguishes Tourmaline from most other gems. It is doubtful this custom is still practiced today considering the value of the gems!
From a resource by Bosi, Andreozzi, Federico, Graziani, Lucchesi: crystal chemistry of the elbaite-schorl series, Minas Gerais, Brazil.
05-13. Tourmaline – dravite #7.
A tourmaline-dravite from Austria.
From the schorl-dravite series resource by Bosi and Lucchesi. Locality: Zillerthal, Tyrol, Austria.
05-12. Tourmaline – dravite #6.
All I did was change the unit cell parameters specs – and out of nowhere came this unexpected star, right in the center of the polyhedra. Fun!