Opal is a hydrous silicate that forms as a precipitate or a replacement of the skeletons of marine organisms. Many colors and varieties of opals occur worldwide. Opals are useful in the production of jewelry, abrasives, insulators, and porcelain. Under ultraviolet light, opals will often fluoresce a yellow or green color. Opals form as veins, crusts, and globule, but never as crystals. Because it does not have a definite crystal structure, opal is classified as a mineraloid, rather than a mineral.
An information card with details on the mineraloid formation, characteristics, and uses is included. Typical samples sizes are generally 1-2 inches in length or width but can vary based on availability and natural crystal shape.
WARNING: CHOKING HAZARD-Small Parts. Not for children under 3 years.
May have sharp edges.