Agates

Jewelry made with the gemstone agate. Agate is one of the most varied and desired forms of chalcedony. Chalcedony is one of the many varieties of quartz. Scientifically classified as a cryptocystalline or microcrystalline quartz, it has a hardness of 7. Quartz, in all its forms, is the single most abundant mineral on earth, making up almost 12% of the earth's crust.