<p>schorl (black tourmaline) NaFe2+3Al6(BO3)3Si6O18(OH)4
locality: Dolní Bory, Czech Republic
photo (c) 2013 Jan Helebrant
</p>
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<a rel="nofollow" class="external text" href="https://www.flickr.com/people/96541566@N06">Jan Helebrant</a>
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/96541566@N06/11186165203/">schorl (black tourmaline) NaFe2+3Al6(BO3)3Si6O18(OH)4</a>