5.3" Polished Laguna Agate Slice - Wegeler Effect

Laguna agate is a highly sought after variety of banded chalcedony. It often forms in bands of red, pink, white, and scarlet hues, and some specimens even contain bands of brown and golden yellow chalcedony. The first documented finds of this agate occurred in the late 1940s: since then, these agates have been extracted from several sites near Ojo Laguna, Chihuahua, Mexico. They are roughly 38 million years old.

Like many other agates, Laguna agates form by deposition of microscopic silica crystals in concentric layers within cavities of rocks. The colors of the agate are dependent on impurities within the silica-rich solutions, of which are often supplied by the surrounding rock.

The Wegeler effect, also known as the shadow effect or parallax effect, is a three-dimensional oddity in which rotating a banded agate creates the illusion that those banding lines move. One line will move with the source of light while the other moves with your point of view. This occurs in agate that has tightly packed, alternating bright opaque bands and transparent bands.