If there really are fairies in this deep-down fairyland of change--and surely there must be--I should say they were the very same fairies we find in a lump of sugar--the crystals. For it is when these crystals take different shapes--the very thing fairies are always doing, you know--that things change into something else, so different you can hardly believe it. One could easily believe that charcoal and coal are related, they look so much alike in the face; but who would say that a piece of charcoal and a diamond were made of the very same stuff? They are. But diamonds are made of crystals and charcoal is not; and that must be it. The carbon of the charcoal was never touched by the wand of the Crystal Fairy. [Illustration: SIX MEMBERS OF THE CRYSTAL FAMILY Introducing six interesting members of the crystal family. The crystals of common salt and of gold, among others, take the form shown at _A_. Alum and diamonds crystallize as shown at _C_; while _B_ and _F_ belong to a system of crystals which we find built up into ice and arsenic. _D_ and _E_ are building-blocks for green vitriol, borax, and sulphate of soda.] A strange thing is that big crystals are always made up of little crystals. So what looks like one crystal is really a United States of crystals, all like each other and each like all of them put together, much as our federal government repeats the form of the State governments, and the State governments duplicate the government at Washington on a smaller scale. [Illustration: THE SAND GRAINS AND THE CRYSTAL FAIRIES The crystal fairies often give battered sand grains a new lease of life and these pictures show how they do it. Fig. "_a_" is a single sand grain which has grown into crystal form; "_b_" shows parallel growths about a grain; "_c_" is a group of neighboring grains that have crowded each other so in their growth that the crystal facets have been destroyed. Sounds odd to speak of sand grains "growing," doesn't it? But they do!] But why do the little crystals always come together in just such a way as to make big crystals shaped exactly like themselves? Goodness knows! But whatever the how and the why of it may be, not only do the crystal people stick as closely to the family pattern in dress as the Scotch Highlanders do to the plaids of their clans, but the crystals are clannish in another way. When a clay rock, for example, is dissolved by the heat, moisture, and chemicals down in the land of change, the particles of the same kind that are scattered through it hunt each other out, and ever after cling together, like Emmy Lou and her "nintimate friends." You've noticed how "spotty" granite is, haven't you? This is because it is made up of different kinds of minerals; but, although the crystals in all follow the granite pattern, the particles of each kind of mineral "flock together." The feldspars and the micas never mix. JUST TRY IT WITH A PIECE OF PAPER