Bismuth and Blue
First of 5 images in a row of the mineral bismuth, a metal that has some radioactivity and is often laboratory-grown to produce such large crystals. This area of the specimen is about 2 inches across. Hard to focus handheld, but I sure tried about 40 shots anyway. In different light it will catch rainbow colors. See the links below for fascinating information about bismuth and how it can be grown.
Seriously, you could make these at home!