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July-August 2014

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Letters to the Editor


I just finished reading the January/February issue on diamonds. This is a personal first where I read all articles start to finish in detail. You managed to assemble a diverse set of perspectives (facets!) on an amazing native element mineral. Plus you artfully limited subject overlap, and the cross references reinforced to covalent bonding of this edition's contents. It's certainly a gem to keep.

Congratulations on great content, entertaining stories, and attractive illustrations.


We are pleased to present the two winning entries in the photo competition held this past February in conjunction with the Tucson Gem and Mineral Show. Their names were announced and their photos shown at the show's Saturday night awards banquet. John Jaszczak won in the microspecimen category and Lance Long in the macrospecimen category.

Cuprite, 2-mm field of view, from Calumet, Michigan, by John Jaszczak, won first place in the micromineral category of the 2014 photo competition. Tom Rosemeyer specimen.

Pyrite, 2.3 cm high, from Rensselaer, Indiana, by Lance Long won first place in the macromineral category. Debra Long specimen.


The Colorado School of Mines Geology Museum (CSMGM) in Golden, Colorado, invites all those in town for the Denver Gem and Mineral Show (12–14 September) to attend our annual open house on 10 September 2014, 6–9 P.M., the Wednesday evening preceding the show (whose theme this year is Agates). Come enjoy our displays and visit with our Museum Advisory Council members, student aides, volunteers, and Friends of the CSMGM, and also browse our expanded gift shop. Again this year we are encouraging mineral dealers and corporations to help sponsor the event, for which they will receive special recognition in return for their kindness. (Please phone for details.)

Every year we strive to change 20 percent of our exhibits to make our museum more exciting for returning guests. As of this writing (early March), we have firm commitments from Lou and Diana Conti, who have graciously offered to loan us their impressive pseudomorph collection. Other tentative plans include a loaned display of minerals from the San Juan Mountains of southwestern Colorado, as well as improved gem, gold, fossil, micromount, educational displays, and other surprises—possibly the relocation of our Irwin Hoffman mining murals (to avoid the water damage they almost received during last year's open-house deluge).

As always, our gala offers free hors d'oeuvres, a cash bar, another relaxing performance by the harmonious Colorado School of Mines String Quartet, and the opportunity to meet other collectors. We hope to see you there.


In “A Re-discovered Twin Law in Kyanite from Africa,” Peter B. Leavens and we wrote (p. 164) that the twin law {12} was not found in “references … in the major literature in the more than 130 years since Bauer's [1878] paper.” This includes the intensively researched Handbook of Mineralogy (Anthony et al. 1995), which does cite other twin laws. However, we have recently discovered that our statement is untrue. The excellent book Crystal Habits of Minerals, by the Bulgarian authors Ivan Kostov and Ruslan Kostov (1999), contains the eye-opening sentence (p. 203): “Twins on {100} are very common, others with twin axes perpendicular to (100), (1), [001], [010] and [41], simple or polysynthetic twins are also known.” Kostov and Kostov's (1) is one of two faces in the form {12} that we described in our article, the other face being (12) itself. In addition, twinning (by rotation through 180 degrees) about an axis perpendicular to any face (hkl) produces a result identical to twinning by reflection across that face (Phillips 1956). This is true if the mineral in question has a center of symmetry, which is the case for kyanite. Thus Kostov and Kostov's description of this twin law is equivalent to ours, even if it looks different.



Anthony, J. W., R. A. Bideaux, K. W. Bladh, and M. C. Nichols. 1995. Handbook of mineralogy. Tucson, AZ: Mineral Data Publishing.

Kostov, I., and R. Kostov. 1999. Crystal habits of minerals. Sophia, Bulgaria: Pensoft.

Phillips, F. C. 1956. An introduction to crystallography. New York, NY: Longmans, Green, and Company.

Richards, R. P., J. S. White, and P. B. Leavens. 2012. A re-discovered twin law in kyanite from Africa. Rocks & Minerals 87(2): 162–67.


The footer on pages 179–182 of the March/April 2014 issue should have read Volume 89, March/April 2014. We thank John Jaszczak of Michigan Technological University in Houghton, Michigan, for bringing this to our attention.


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