1 The stone is a unit of measure which, at the time it ceased to be legal for trade in United Kingdom in 1985, was defined in British legislation as being a weight or mass equal to fourteen avoirdupois pounds (about 6.35 kilograms).
2 When the pH of acid mine drainage is raised past three, either through contact with fresh water or neutralizing minerals, previously soluble Iron ions precipitate as Iron hydroxide, a yellow-orange solid colloquially known as Yellow Boy. Other types of iron precipitates are possible, including iron oxides and oxyhydroxides. All these precipitates can discolor water and smother plant and animal life on the stream bed, disrupting stream ecosystems.
3 The Banach–Tarski paradox is a theorem in set theoretic geometry which states that a solid ball in three-dimensional space can be split into a finite number of non-overlapping pieces, which can then be put back together in a different way to yield two identical copies of the original ball. A stronger form of the theorem implies that given any two “reasonable” objects (such as a small ball and a huge ball), either one can be reassembled into the other. This is often stated colloquially as “a pea can be chopped up and reassembled into the Sun.”