If you’ve watched any Star Trek from the Next Generation on, you’re probably familiar with the Borg and their giant gray cube-shaped ships. Galena is the Borg cube of the mineral world. It often forms in silvery gray cube shapes that, like some fluorite, are often made up of smaller cubes, making them look even more Borg-cubelike. Although Borg ships and galena might float in space, both of them are very heavy, and in galena’s case, that’s because it’s made of lead. Not only can galena and fluorite have similar shapes, they often also occur together because they both usually have a hydrothermal origin—they form from minerals dissolved in super-hot fluids underground. When you find or buy a combo specimen, there’s a really nice contrast between the silvery gray galena and colorful candylike fluorite. Galena is also the main source of lead, and sometimes some real silver sneaks in there too, so you can get some silver when you melt it down. One warning: like many other lead-based minerals, mercury-based minerals, arsenic-based minerals, etc., galena can be toxic, so smart rockhounds always wash their hands after touching a galena specimen, in case they accidentally lick their fingers afterwards.