Guess the Mineral (3)

Guess the Mineral (3)

Author: ChemViews & Chemie in Unserer Zeit

2014 is the International Year of Crystallography (IYCr). We have taken this opportunity to design, together with the journal Chemie in Unserer Zeit (ChiuZ), a new quiz. The idea is that you guess the name of a mineral with the help of an image and some tips.

We will publish a different question in each of the following months: April, June, August, October, and December. Everyone who gives the correct answer before the required date will be put into a draw to win a book published by Wiley–VCH. For each question there will be two lucky book winners. In addition, at the end of the year we will draw one winner from among all the correct answers to receive an iPad.
So contribute, it’s worth it!

We thank Ekkehard Diemann, University of Bielefeld, Germany, who has made this quiz possible by providing the beautiful images and the texts accompanying these quiz sections.
For tips on how to take such pictures by yourself, read his article on Digital Photography in Chemistry.

3rd Mineral

Our mineral (pictured abovve) crystallizes in orthorhombic barite-type crystals of the space group Pnma. It forms rhombic dipyramidal crystals in, for example, deposits in fractures and solution cavities in limestone, but also, as in our example, fibrous structures.

The name of our mineral refers to the often bluish color of the crystals. This color is due to F-centers, a type of cystrallographic defect that forms when strong radiation (cosmic radiation, radioactive minerals) excites electrons which then are captured by vacancies of the anionic lattice.

What is the name of our mineral?

Send your solution indicating your address before September 22, 2014 to [email protected]

–> The answer to this quiz has been published

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