I’m about to lose my mind guys. Sit down, strap in, and get ready to learn about this glorious Mineraloid until your eyes bleed. OPAL.
Mineraloid? What does that mean you ask? It means opal isn’t technically a mineral, because it doesn’t have any sort of ordered crystalline structure. Its molecules went crazy, so it’s a hydrated, amorphous silica (Silicon Dioxide).
Amorphous materials are solid, but also kind of liquid at the same time. It doesn’t know what it wants to do, like gels or glass. Opal contains anywhere from 3% to 21% water. Nature was all “Opal, settle down bro” and opal was all like “DON’T BRO ME, LIKE YOU KNOW ME” then exploded into colors and dropped the mic.
Look at it go! What a tease. Now let me blow your mind. This rainbow iridescent color thing opal has going on… is actually NOT called opalescence. It’s called “Play of Color.” Opalescence actually refers to the lesser color change in the milky white material.
Play of color in opals is caused by microscopic silica spheres 150 to 300 nm in diameter, scattered in closely packed lattices throughout the opal. These tiny balls cause light wavelengths to overlap and bend. The relative size of the spheres, and the distance between them determines the quality of the opal and the color.
Comes in Geode form too. Geodes are just neat. Oh look at this boring ugly rock— NO YOU FOOLS, INSIDE I’M A SUPERHERO!
JESUS CHRIST OPAL WHAT ARE YOU DOING NOW? Lodging yourself in some ironstone like a ninja, to further loosen my questionable hold on sanity? Yeah that sounds about right. This kind of opal is called boulder opal and comes from Australia.
Sometimes Opal gets bored just riding around in the rocks. This opal formed in some petrified wood. Aptly called opalized wood. It can also do this with bones. When I die, I want to be an opal.
Black Opals, such as these, are far rarer and way more valuable than diamonds.
Opals are a tricky beast though. The water content in an opal is extremely important to maintaining its integrity. After an opal is unearthed, the normal atmosphere may not have enough humidity for it to maintain it’s water levels, and it will “craze” as it’s called. Basically dry out and crack, lose all it’s awesome color play, or become milky white.
Opal sellers will store opals for up to two years before unloading them to ensure the opal is stable and won’t craze. Opal is also about as hard as glass too, so ease up off it’s back.
Look at this squiggly bulls**t. That’s amazing. I don’t even have the time to go into the different types and sub types of opals, which is probably for the best, as I’m sure everyone at this point needs a few moments to get cleaned up and change their pants.