Chalcedony. A semi-important gemstone named after the nearby city of Chalcedon, and is particularly offered in a lot of Istanbul's large number of jewellery stores. Today, most metro stations don't have a staffed ticket booth, so you will need to get hold of your Istanbulkart from the yellow ticket devices. https://is-wordpress-is-free57889.fare-blog.com/37196865/the-single-best-strategy-to-use-for-istanbul-work