Turritella agate

Agate belongs to the silicate group. It contains silicon and has the same chemical formula as quartz or amethyst. Agate is often sold in slabs and sometimes artificially colored, but it is also found in solid form. The color of agates varies along their concentric bands, from colorless to white, passing through blue, brown, gray, and green. Turritella are gastropod mollusks belonging to the Turritellidae family. Turritella lived from the Cretaceous period to the end of the Miocene epoch (145 to 2.5 million years ago).