Chalcedony. A semi-important gemstone named following the nearby town of Chalcedon, and is particularly sold in most of Istanbul's large number of jewellery shops. At present, most metro stations would not have a staffed ticket booth, so you will need to get hold of your Istanbulkart through the yellow ticket https://istanbul-wordpress91233.newsbloger.com/37714415/not-known-details-about-wordpress-kursu-istanbul