smoky quartz crystal cluster - teaching specimen from Novo Horizonte, Bahia, Brazil

Teaching smoky quartz cluster from Município Novo Horizonte, Bahia, Brazil. This area is famous for smoky quartz, often with rutile inclusions in the crystals.

Smoky quartz forms from natural gamma radiation released by surrounding rocks. The radiation causes aluminum atoms, which replace silicon atoms in the crystal lattice, to transfer an electron to a neighboring positively charged ion, often Li+, forming an aluminum metal color center that darkens the quartz.

These attractive clusters are washed, but but otherwise are as collected. Often, the faces of gemmy smoky quartz crystals in a cluster are polished. These are useful as teaching specimens, with crystal faces as they came from the mine and perfect terminations..

The pencil is 5 1/2" long, for  scale.

Select a specimen: When more than one specimen is shown, you can select a particular specimen by telling us what is in the photo with it, either a black and silver pen, a black mechanical pencil (it has an eraser), or one of those plus some number of coins, or you can let us make the selection.

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