Yerevan Vernissage (arts and crafts market), close to Republic Square, bustles with hundreds of vendors selling a variety of crafts on weekends and Wednesdays (though the selection is much reduced mid-week). The market offers woodcarving, antiques, fine lace, and the hand-knotted wool carpets and kilims that are a Caucasus specialty. Obsidian, which is found locally, is crafted into assortment of jewellery and ornamental objects. Armenian gold smithery enjoys a long tradition, populating one corner of the market with a selection of gold items. Soviet relics and souvenirs of recent Russian manufacture nesting dolls, watches, enamel boxes and so on are also available at the Vernisage.

Answer this question, if possible (if impossible, reply "unanswerable"): What is Obsidian used for?
jewellery and ornamental objects