Scientifically speaking, the term “crystal” refers to any solid that has an ordered chemical structure. This means that its parts are arranged in a precisely ordered pattern, like bricks in a wall.

Crystals can do all sorts of things, some more useful than others. They can separate the gullible from their money in New Age healing shops. But they can also serve as the light-harvesting layer in a ...

One of the reasons gold is so valuable is because it is highly unreactive—if you make something out of gold, it keeps its lustrous radiance. Even when you can react it with another material, it’s also ...