April

Garnet, Olivine, Silver, Topaz, Zoisite (2),

04-30

Posted on by Jean Constant

04-30. Dolomite #1.

A strange flower coming down from the Italian Alps? Not quite – the mineral dolomite is named after Frenchman and mineralogist Deodat de Dolomieu in the mid-1700s.

Dolomite is the mineral for week #18 of the 52-week tour of the geometry of Nature. It is usually found in clusters of small rhombohedral crystals – small parallelepiped where all edges are the same length – and has a somewhat “saddle”-like shape. Its color varies from white to tan to pink. It’s part of the trigonal system family.

Dolomite is not often encountered as a gem. It is generally known as an inclusion in emerald, garnet, quartz, and ruby. A fascinating article by Luo, Yang and Shen describes its possible association with nephrite and how it was used in ancient Chinese culture. A major source of magnesium, it is found today in pharmaceutical applications and agricultural products.

From a resource by Steinfink & Sans: refinement of the crystal structure of dolomite.

04-30

04-28

Posted on by Jean Constant

04-28. Garnet #6.

The garnet structure is so well balanced and symmetrical, its geometry does make for traditional stain glass window template!

From a resource by Ross, Keppler, Canil and O’Neill.

04-28

04-25

Posted on by Jean Constant

04-25. Garnet #3.

What more to say!

The structure of this garnet crystal is so awesome, I just highlighted a few spots here and there.

Now, the most surprising for me is that antic and medieval jewelry takes so much after the geometry of the crystal, I wonder how they did it, not having any of the sophisticated instruments we have today to study nano-size objects.

There are 365 atoms, 642 bonds, 107 polyhedra in this image – not counting the few gems I inserted on the original geometry.

From a resource by Griffen, Hatch, Phillips and Kulaksiz.

04-25

04-23

Posted on by Jean Constant

04-23. Garnet #1.

Just in time to celebrate Earthday weekend – a bouquet of garnets!

341 atoms, 538 bonds, 99 polyhedra went into the structure of that feisty little mineral.

Garnet will be the mineral of week #17 in this 52 weeks tour of the geometry of nature. Garnet is a set of closely related minerals – more than twenty categories that result in gemstones in almost every color. Their crystal belongs to the cubic system, built around three axes that are all of equal length and perpendicular to each other.  

Last January, I explored a rhodonite crystal, one of the subcategories of the garnet family. This time I’ll look into the generic structure of the mineral.

Garnets can be found all over the world. Some carved ones were found in the former Czechoslovakia or Egypt as far back as the Bronze Age. They were used in Sumer as well as Sweden before 2000 B.C. Native American Indians, South American Indians, Aztecs, and Mayans used it as a sacred stone.

This first visualization was extracted from a resource by Fujino, Momoi, Sawamoto and Kumazawa.

04-23

04-22

Posted on by Jean Constant

04-22. Olivine #7.

1,403 atoms, 2,628 bonds, 490 polyhedra! The polyhedra setting makes for a splendid background pattern. I also included the full olivine structure as little cubes on a shelf.

Resource from Muller-Sommer, Hock and Kirfel.

04-22