Agate is a type of chalcedony, which is a variety of quartz. It is known for its beautiful banded patterns and vibrant colors. Agate crystals form in volcanic rocks and are often found in geodes or as nodules in sedimentary rocks.
 
Agate crystals have a Mohs hardness of 6.5 to 7, making them relatively durable. They have a vitreous or waxy luster and can be translucent or opaque. The colors of agate can vary widely, including shades of white, gray, blue, green, pink, and brown. The characteristic banding in agate is caused by alternating layers of different mineral compositions.
 
Agate crystals have been valued for thousands of years for their beauty and believed metaphysical properties. They are often used in jewelry, carvings, and decorative objects. In the metaphysical world, agate is thought to bring balance and harmony, promote emotional healing, and enhance mental clarity.