It's tricky to find minerals that are *perfectly* box-like, as that shape is more common in crystals grown in a lab setting. However, two minerals known for their cubic crystal habit are:

1. Pyrite: Often nicknamed "fool's gold" due to its metallic luster, pyrite commonly forms in cubes. Its crystals can be found in a variety of sizes, from microscopic to several inches across.

2. Halite: This mineral is simply table salt! Halite also commonly crystallizes in cubes, which is why you often see salt in square-shaped crystals.

Keep in mind that the shape of a mineral can vary based on its formation conditions. While these two minerals are known for their cubic habit, you may find specimens that have irregular shapes or are just fragments of the original cube.