Opal is a hydrated amorphous form of silica (SiO 2 · n H 2 O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) …

Mar 5, 2025 · Opal is a fascinating mineral known for its unique play of colors and diversity. There are many types of opal, each with distinct characteristics that make them special. For …

Opal is one of the world's most popular gemstones and the birthstone for the month of October. A nice precious opal can flash every color of the spectrum with an intensity and quality of color …

Apr 11, 2019 · Opal is a mineraloid or crystalline form of silica. It is colorless when pure. The Precious forms of Opal occur in a wide variety of colors, including white, yellow, red, orange, …

Opal is an October birthstone. Grids of silica spheres 0.2 microns in size create red play-of-color flashes. Opal contains up to 20% water trapped in its silica structure. The novel “ Anne of …

May 15, 2025 · Opal, silica mineral extensively used as a gemstone, a submicrocrystalline variety of cristobalite. In ancient times opal was included among the noble gems and was ranked …

Jul 1, 2024 · Opals are a unique and mesmerizing gemstone known for their distinctive play of color, making them one of the most sought-after and mysterious gemstones in the world. In …

Although it is still (2007) regarded as a mineral species for historical reasons, opal is not a true mineral in the accepted sense of the word as it is variably composed of poorly crystalline …

Opal, being amorphous, is not truly a mineral but a mineraloid. One of the scientifically accepted standards defining a mineral is that a mineral must have a crystal structure, which opal lacks. …

Aug 11, 2021 · Opal gemstones are hydrated silica crystals that form over millions of years. Learn about opal details, including stone meanings and symbolism, history, pricing, and value.