Smoky quartz ranges from a brownish gray to black. The lighter crystals are transparent, while darker ones are opaque. 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 points were mined from cavities in a pegmatite near Diamantina in Minas Gerais, southeastern Brazil.
Useful teaching specimen, with perfect termination at one end. Click large image for a larger view.
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, a black and silver pen, a black mechanical pencil, or one of those plus some number of coins, or you can let us make the selection.
Making multiple purchases? Click on the "combine shipping" button in the shopping cart. We'll send an invoice with combined shipping. A link in that invoice will bring you back to checkout, no hassle.
Shipping: By Priority Mail or USPS Ground Advantage, whichever is cheaper. Click > here < for shipping rates. See comment at Note! Use back button to return to this page.
