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Chrysoberyl Trilling
Based on a specimen from Novello Claims, Zimbabwe
This model was one of the most labor intensive I ever made, and occupied the entire winter of 2026. Although it turned out well, it was an extremely difficult and complicted model to make. Every set of pieces was a challenge - reverse bevels, extremely narrow pieces, angles over 45 degrees, and complex assemblies of pieces that had to be cut and assembled in multiple stages. Not to mention the surprising complexities introduced by including the dotted line! Most of my models include a challenge or two, and I’m happy to have them since they drive me to improve my technique. But every aspect of this model seemed to present a new issue.
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Quartz - Dauphine twin
Based on a specimen from Uri, Switzerland
The Dauphine twin law is a parallel axis twin combining either two left or two right handed quartz crystals. Quartz is commonly twinned according to the Dauphine twin law, but specimens exhibiting ideal form are less common than might be expected. Faces that would reveal twinning are not always expressed, and twin boundaries are often irregular and hard to see. That means in a crystal whose faces don’t reveal its handedness, twinned regions with seamless boundaries can pass unnoticed. (Models of quartz crystals whose handedness can be determined are shown here)
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Quartz - Brazil twin
Based on a specimen from Canton of Graubunden, Switzerland
The Brazil twin law is a parallel axis twin found in quartz, combining a right and a left handed individual. Ideal drawings of a fully developed, symmetrically twinned crystal are often found in textbooks, and make for some really lovely diagrams (see below for one of them). Unfortunately, actual crystals with these faces are extremely rare, but it’s possible that I have one in my collection. More about that below, but first here’s a wood model representing the ideal form, depicted in fig. 455 from Dana’s A Textbook of Mineralogy, 4th ed., edited by W. E. Ford.
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Pyrite - Iron Cross Twin
Based on a specimen from Gachala, Cundinamarca Dept., Colombia.
One of the most recognizable crystal drawings in any mineralogy textbook is the diagram of the pyrite iron cross twin. It’s a penetration twin of two pyritohedra, and their interaction creates the distinctive cross-shaped pattern where the edges of the two pyritohedra intersect at 90 degrees. Below is a drawing from a crystallography textbook, with the model I made next to it.
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Calcite - Twinned and Untwinned Scalenohedra
Based on specimens from Ohio and Tennessee
One of the most distinctive forms that calcite takes is the scalenohedron, recognizable by its alternating pairs of faces with steeper and shallower intersections, all meeting in the center to produce an equatorial zigzag. Although there are many possible scalenohedra, ranging from squat to extremely pointy, the form {21.1} is the most common. Both of these models represent that form. One shows the scalenohedron alone, and the other shows an idealized twin of the same form on (00.1).
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Spinel - Spinel Law Twin Display
Based on a specimen from Luc Yen Mine, Yen Bai Province, Vietnam.
I love the idea of displaying a mineral inside a box or case that’s a matching crystal model. It seems like a perfect way to show off a specimen with particularly good form, and present an impressive or surprising specimen in a unique way. This twinned spinel specimen isn’t perfectly smooth or gemmy like some smaller crystals in my collection, but its large size made it the perfect candidate for a custom display.
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Staurolite Fairy Cross Twin
Based on a specimen from Semiostrovie (Sevev Islands), Russia.
When I was a kid, every attraction with any kind of geologic connection (museums, national parks, commercial caves) had a basket of staurolite fairy crosses for sale in the gift shop. Some of them were probably fakes, some of them were “improved” by a little judicious carving, and some of them had cheap findings glued to one end to turn them into pendants. I never bothered to buy one back then, because they seemed cheesy and incredibly common. Lately however, a well formed fairy cross is a little harder to come by. I’m keeping my eye out at mineral shows for a specimen that more closely resembles the form of the crosses I remember from my childhood, but this one from Russia will do nicely for now.