Agate is the most creative stone made by "Mother Nature". Agate is chalcedony formed from layers of quartz. As a general term, agate is so broadly descriptive that there are hundreds of names applied to varieties of agate from different localities. While many names reflect the source, some popular varieties are descriptive, such as "blue lace agate". The stone was given its name by Theophrastus, a Greek philosopher and naturalist, who discovered the stone along the shoreline of the river Achates sometime between the 4th and 3rd centuries BC. Agate's most noticeable metaphysical and healing properties properties overall are balancing yin/yang energy, courage, protection, healing, and calming.